Long before Mark Cuban became a household name as an investor on Shark Tank, the owner of the NBA’s Dallas Mavericks, and one of the richest people in the world, he was hustling in far less glamorous ways. To pay for his junior year at Indiana University in the early 1980s, Cuban ran a “chain letter” out of his dorm room, as he recounted on the San Francisco Standard’s Life in Seven Songs podcast in 2024.

The scheme began with a single person, whom Cuban approached and asked for $100—the seed of what he readily describes as a Ponzi scheme, or a “scam.” Chain letters of that kind only keep paying as long as new participants keep feeding money up the line—the same structure that took its name from 1920s con artist Charles Ponzi.

“I’m going to take $50 of that. And here’s a list of 10 names,” Cuban told that person. “We’re going to send 50 bucks to whatever dorm room that this person at the top of the list is. Then we’re going to take their name off the list and put your name at the bottom. So we’ll make it a $50 chain letter. And as everybody else does that, your name moves up the list until you’re at the top. And as we grow the chain letter, hopefully you’ll get more money than you put out.”

It might sound like an early lesson in social capital. “No, no. It was basically a scam,” Cuban, now 68, said with a chuckle. “I made sure my friends all got their money back. And so I got up to the top of the list. And it was amazing, because I’d go to [my mailbox] and there’d be envelopes with 50 bucks from here, 50 bucks from there, and that’s how I paid for my junior year of college.”

That kind of cash meant a great deal at the time. Cuban came from humble beginnings, growing up in a working-class family in a suburb of Pittsburgh. His father, who worked in car upholstery, would occasionally hand a $20 bill, but Cuban was constantly searching for ways to make money of his own. That drive traces back to his childhood, when he asked his dad for a new pair of basketball shoes and was told that once he had a job, he could buy whatever he wanted.

The exchange launched Cuban on a long career of entrepreneurship—one that began, of all things, with trash bags. A friend of his father had boxes of trash bags to unload and told Cuban he could sell them, so he went door-to-door around his neighborhood peddling the household staple.

“I would go door-to-door to be like, ‘Hi, my name is Mark. Do you use trash bags?’” Cuban recalled. “I killed it.”

How Mark Cuban Became a Billionaire

After college, Cuban moved to Dallas—years before he would become the face of the city’s NBA franchise. He worked there as a software salesman and shared an apartment with five other guys in what he called a “s–thole.”

“It was nasty as can be,” Cuban said. “I slept on the floor, and if somebody was of town, I got a bed. I didn’t have my own closet, didn’t have my own drawers. Nothing.”

During that period, Cuban absorbed everything he could about computers and software—even if that meant sitting down and reading manuals. Then came a turning point: while working as a salesman, he stood to earn a $1,500 commission, money that would have helped him move out of the apartment he and his roommates fondly called the “hell hotel.” But when he went to pick up the check, his boss fired him on the spot.

That moment inspired Cuban to start his first company, MicroSolutions, which wrote software for PCs. He sold it for $6 million in 1990.

For a while afterward, Cuban bought a “lifetime pass on American Airlines, partied like a rock star, and just traveled,” he said.

“I was young, single, and crazy, and there were no limits,” Cuban said. “I just wanted to have a beer with as many people as I possibly could, experience as many things as I possibly could.”

His entrepreneurial trajectory then soared. In the mid-1990s, Cuban and two friends, Cameron Christopher Jaeb and Todd Wagner, founded the internet radio company Audionet.com, which was later renamed Broadcast.com. At the height of the dotcom bubble in 1999, they sold the company to Yahoo for $5.7 billion, cementing Cuban’s status as a billionaire. The sale came just before the bubble burst the following year.

Over the following decades, Cuban focused heavily on business investments and starred on Shark Tank, backing startup companies on the show. In 2000, he purchased a majority stake in the Dallas Mavericks. He parted ways with Shark Tank in 2025, and in late 2023 he sold his majority stake in the Mavericks for $3.5 billion. Cuban is currently worth an estimated $10.4 billion, according to Bloomberg.

The primary reason he stepped away from the Mavericks? To protect his three kids.

“Running a professional sports team is always good when you’re winning. It’s great,” Cuban said. “But when you’re having a bad season, and [my] kids are on social media, I just didn’t want them to put up with everything.”

Now, Cuban has moved on to very different ventures. In 2022, he launched Mark Cuban Cost Plus Drugs with a mission to eliminate the middleman from the pharmaceutical industry—a system he identifies as the major culprit behind high drug prices.

“Disrupting an industry that everybody hates, that’s fun,” Cuban told Wired in 2024.

A version of this story originally appeared on Fortune.com on Oct. 10, 2024.