“Is this technically Dumbo?” Billy McFarland asked, walking toward the East River shoreline. “It’s super cool. Are the rents here crazy too?

“I never spent much time in Brooklyn, until the Brooklyn detention center,” he continued. “I was always like, ‘I’m never going to live in Brooklyn.’ Now, I think it’s kind of nice.”

Mr. McFarland, who in 2018 entered guilty pleas for fraud stemming from his role in organizing the Fyre Festival — a Coachella-for-the-Bahamas affair that went spectacularly awry and established him as the Elizabeth Holmes of party promoters— had been a free man for all of 15 minutes. And he didn’t seem inclined to lay low after spending close to four years in prison, plus another six months of additional confinement.

Moments after removing an electronic ankle monitor at the Gold Street halfway house where he had stayed earlier this year, he was posing for a New York Times photographer and talking to a reporter whom he’d approached toward the end of his confinement with the help of a publicist.

“I thought it was going to be a big process, but it turns out they just hand you scissors and you cut it off,” said Mr. McFarland, 30, who is 6-foot-3 and post-prison lean. He was wearing a dark T-shirt and navy pants that he said were from Uniqlo. On his feet were Gianvito Rossi sneakers that looked like Converse All Stars, but retail for around $700.

Mr. McFarland — who has little money in the bank, around $26 million in financial amends to make and no immediate job prospects — said he had purchased the shoes before his legal problems.

“Friends joke that my entire wardrobe is from 2016,” he said.

Back then, Mr. McFarland — who grew up in Short Hills, N.J., and dropped out of Bucknell University after less than a year — was known as the founder of a company called Magnises, whose flagship charge card was pitched as a kind of American Express Black card for millennials.

Mostly, those who joined were given access to an open bar at a Greenwich Village townhouse where he held parties. Another membership perk: Bahamian excursions, including to Norman’s Cay, a small island that once served as a hub for the Medellín Cartel’s cocaine-smuggling operation.

That was the site Mr. McFarland had selected to hold an epic coming-out festival for his next invention, Fyre, an Uber-like app through which people could book their favorite celebrities for special events. He enlisted Ja Rule, Kendall Jenner, Bella Hadid and Emily Ratajkowski to help promote the 2017 party, which featured more than 30 musical guests, including Blink-182 and Tyga. Tickets cost up to $12,000.

But the Fyre Festival — which would go on to achieve cultural notoriety, if not for the reasons Mr. McFarland had intended — was poorly planned, and its finances were a mess.

The night before the first attendees arrived on the island, an intense rainstorm hit.

People showed up to find that the “luxury villas” that came with their ticket packages were, in fact, disaster relief tents located on a makeshift camping ground.

And the “uniquely authentic island cuisine” guests were promised in promotional materials turned out to be cheese sandwiches served in plastic foam containers, though Mr. McFarland countered in our interview last week that reports of the meals had been vastly overblown.

“There’s a reason there’s only one photograph of that,” he said, referring to a viral shot of a sad pile of lettuce topped by two tomato slices, above two slices of prepackaged cheese serving as a sort of garnish for two slices of untoasted wheat bread.

Ultimately, the event — which stranded thousands of attendees in the Bahamas and left them scrounging for makeshift shelter on a dark beach — was scrapped without a single performance taking place. Less than two months later, Mr. McFarland was arrested and charged with fraud.

“They took me to the Brooklyn detention center for one night,” he said. “My head was swirling with all these things, and I panicked like, ‘I need to pay everybody back tomorrow or else this is real.’”

Class-action lawsuits followed.

While on probation, Mr. McFarland launched a V.I.P. ticket service that promised users tickets he didn’t have to events including the Broadway musical “Hamilton,” the Victoria’s Secret fashion show and the Met Gala.

There was another round of fraud charges.

“I probably added years on to my sentence by doing that,” he said. “I just was making bad decision after bad decision.”

By the water in Dumbo, Mr. McFarland struck a few plaintive poses. “I can’t wait to go swimming,” he said.

He then took an Uber to his small second-floor apartment in the Bedford-Stuyvesant neighborhood.

On the curb outside his new building, he continued to speak of the borough with tourist-like wonder. “Was this street terrible years ago?” he asked. “Because there are all these nice new buildings.” (Before the Fyre Festival, Mr. McFarland had lived in the meatpacking district. “I was 21 when I moved there — cut me some slack,” he said.)

With characteristic vagueness, Mr. McFarland said the rent for his new place was being paid by “family and friends.” He did not say whether that included his parents, Steven and Irene McFarland, who are real estate developers based in New Jersey.

It had taken a lot, Mr. McFarland said, for his parents to understand that “someone they were so close to was capable of lying like I did.” He continued, “I hurt them, and it sucks.”

Had he personally apologized to his victims? “No,” he said, then posed a question of his own:

“What would you say to them if you were me?”

The terms of Mr. McFarland’s six-month house arrest allowed him to go outside only to go to the grocery store or the gym. He chose a membership at Blink Fitness, which he paid for with a debit card. “I don’t think I can get a credit card,” he said.

His new apartment was Airbnb-neutral. The only decorations were a few plants he’d picked up at Trader Joe’s — a bird of paradise, two money trees — along with a white board that was blank as the decor. The bed was perfectly made, the floor immaculate.

The work of a cleaning service? “You’re never going to believe it,” he said. “I learned how to do it!”

As Mr. McFarland recalled it, his housekeeping education began at the Metropolitan Detention Center in Brooklyn, where he was first held, then continued at the Otisville Correctional Facility in upstate New York, where he was transferred in early 2019. “It was like Danbury,” he said, referring to the less hard-line cushy-by-prison standards facility where Martha Stewart did her time. “But I messed it up.”

Guards confiscated the drive and Mr. McFarland spent three months in solitary confinement, where he said he fell asleep to the sounds of a screaming gang member known as the White Tiger, so named because of tattoos of the animal that covered his face and other areas of his body.

After that, he was resettled at FCI Elkton, a low-security federal correctional institution located in Ohio.

Then, in 2020, the coronavirus pandemic hit. Mr. McFarland appealed for compassionate release, claiming that allergies and asthma placed him in a high risk category for health complications. His efforts were unsuccessful. “Hope clouds your judgment,” he said. “There was no way I was going to get out.”

Ultimately, prison records show, Mr. McFarland spent six months there, though the records do not specify why. His lawyer, Jason Russo, said in a phone interview that he had written letters to prison officials attempting to get Mr. McFarland out of solitary confinement, only to be stonewalled at every turn. Mr. Russo said he could not even get a specific answer as to why Mr. McFarland was there for such an extended period of time. Emails and phone calls to the prison by the New York Times were not returned.

Mr. McFarland read a lot during those months. “There was nothing else to do,” he said.

One of the books he finished was Simon Sinek’s “Start with Why: How Great Leaders Inspire Everyone to Take Action.” Another was Gregory David Roberts’s novel “Shantarum.”

“It’s about an Australian who breaks out of jail and joins the Indian mafia,” said Mr. McFarland. “Really cool.”

In Mr. McFarland’s Bedford-Stuyvesant living room, on a small shelf by the gray couch from Wayfair — “A friend bought it for me,” he said, “I couldn’t afford it” — were copies of Don Winslow’s “City on Fire” and Sebastian Mallaby’s “The Power Law: Venture Capital and the Making of the Future.”

But Mr. McFarland said hadn’t been doing as much reading since he began home confinement and acquired a Mac desktop computer with a Westinghouse screen. “I just missed the computer so much,” said Mr. McFarland. “I missed that more than anything.”

As part of his plea, Mr. McFarland is barred for life from serving as a director of a public company. His earnings will be garnished until he pays back the full amount he owes his victims, more than $25 million.

“Obviously, he’s got a lot of work ahead of him,” Mr. Russo said.

At least for now, Mr. McFarland has abandoned the idea of writing his memoir.

“The book’s not going to pay the restitution, let me put it that way,” he said.

So what will?

“I’d like to do something tech-based,” he said a few minutes later, walking to BKLYN Blend, where he ordered an egg sandwich and a coffee. “The good thing with tech is that people are so forward-thinking, and they’re more apt at taking risk.

“If I worked in finance, I think it would be harder to get back,” he continued. “Tech is more open. And the way I failed is totally wrong, but in a certain sense, failure is OK in entrepreneurship.”

Seated at a quiet table in the corner — no one at the coffee shop appeared to recognize him — Mr. McFarland mulled whether he’d prefer to work for himself or someone else. “At the end of the day, I think I could probably create the most value by building some sort of tech product,” he said. “Whether that’s within a company or by starting my own company, I’m open to both. I’ll probably decide in the next couple of weeks which path to go do.”

He said he was “not particularly interested in crypto,” though he would make an exception for the latest frontier in blockchain technology, decentralized autonomous organizations, which he said were “allowing people to come together online to effect real world change in a way they previously couldn’t, taking people to places they couldn’t get to — and, once they’re there, enabling them to effect real-world change.”

In April 2020, while in prison, Mr. McFarland made his first foray into philanthropy. He led a drive called Project 315, which raised money to cover the costs of calls between underprivileged inmates and their families. Four days after the project’s Instagram launch, fees were waived nationwide. “We did it,” the Instagram account associated with Mr. McFarland’s “non profit organization” said, claiming credit. (In fact, the suspension of fees came after campaigning by Senator Amy Klobuchar and a group of other Democratic senators that had begun well before Mr. McFarland got the idea.)

But it whetted his appetite for good works, he said. Now, Mr. McFarland is talking about forming a charity that would pay travel costs for the families of prisoners.

“I met some really amazing people in prison,” he said. “Half the people are just naturally bad and the other half are great.” (Mr. McFarland hedged, when asked which group he belonged to. “But I think I’m a better person than I was four years ago,” he said.)

Mr. McFarland said he wanted people to know that he was sorry for what went wrong with the festival and for his actions. “I deserved my sentence,” he said. “I let a lot of people down.”

He attributed his choices in part to “immaturity” and hubris.

“I didn’t know what I didn’t know,” he said.

Partly, he blamed the tech world — the very same world he was musing about re-entering — which he said sometimes operates by an “ends justify the means” ethos.

Still, he took some issue with news articles that compared him to Bernie Madoff; he wasn’t running a decades-long scheme to defraud people of their life savings, after all. Plus, he said, he hadn’t planned for things to end up the way they did.

Much was made in both the Hulu and Netflix documentaries about the local workers in the Bahamas who were stiffed when the festival was canceled and debts piled up.

Mr. McFarland argued that this characterization was somewhat misleading because, he said, most of them were working on a day-to-day or week-to-week basis, and therefore suffered limited losses. (One restaurant owner said in the Netflix documentary that she spent $50,000 of her savings preparing for the festival and received no compensation from organizers. In May 2017, she told The New York Times that she was owed $134,000.)

Two of his former Bahamian employees traveled to New York for a post-house-arrest party Mr. McFarland hosted on the evening of his release at Marylou, a French bistro in the East Village.

Ozzy Rolle, Mr. McFarland’s principle consigliere in the Exumas, an island district in the Bahamas, said the following afternoon that he’d been paid almost everything he was owed for the festival, before it imploded. “I was treated good. Probably a week I wasn’t paid for.” He even went as far as to say the Fyre Festival had been good for tourism in the Bahamas. “So many people came after reading about what happened,” he said.

But Scooter Rolle, his cousin and travel companion, said he had yet to get a dime of what he was owed for his work, in the days before Fyre. “I came to clarify things,” he said.

That didn’t exactly happen, but Mr. McFarland did buy him a post-party lobster roll at Sarabeth’s Kitchen. “Billy tried his best,” he said.

Back at the Bed-Stuy cafe, Mr. McFarland said the biggest sin he had committed was digging himself in deeper with dishonesty.

“I lied,” he said. “I think I was scared. And the fear was letting down people who believed in me — showing them they weren’t right.”