Mark Cuban says he only felt successful for the first time at age 28: My dad 'broke down in tears and started sobbing'

Billionaire investor Mark Cuban vividly remembers the moment he finally felt successful — because he spent so many years beforehand trying to stave off being flat broke.

In his 20s, Cuban shared a three-bedroom apartment with five roommates and used grocery store hacks to pinch pennies. Fired from a tech sales job, he started a software company called MicroSolutions that gained momentum quickly — $15,000 in revenue in its first two months, Cuban recently told GQ — until his secretary stole $82,000 from its bank account, leaving just $2,000 behind.

Roughly a year later at age 28, after rebuilding his startup nearly from the ground up, Cuban reached a personal milestone that told him he'd finally made it.

The turning point "was probably when I had $100,000 in the bank," Cuban, now 65, said. "I remember telling my buddy Dave Winslow, we're sitting at a bar and telling him, being so proud. And telling my dad who just broke down in tears and started sobbing."

Adjusted for inflation, Cuban's $100,000 in personal savings would be worth roughly $280,000 today. That's more than the average American household has in savings — $41,600, according to 2019 Federal Reserve data.

It's also a lot less than the net worth Americans say they need to feel wealthy: at least $2.2 million on average, financial services company Charles Schwab's annual Modern Wealth Survey recently found.

For Cuban, the $100,000 benchmark was a sign that his finances and startup were finally stable, especially following his secretary's theft a year prior.

Losing so much money overnight "was f---ed up, but [it was] the best thing that ever happened to us, because it made us get our s--- together," Cuban told Barstool Sports' "Pardon My Take" podcast in 2020.

His turnaround strategy was simple: He put his head down and worked. At the time, he spent most days reading Cisco router manuals and "sitting in my house testing and comparing new technologies," he wrote in a 2004 blog post.

The effort paid off when Cuban sold MicroSolutions for $6 million in 1990 to CompuServe, a now-defunct internet services company. The deal made Cuban a millionaire at age 32 — a career milestone he topped seven years later, when he sold his next company Broadcast.com to Yahoo for $5.7 billion in 1997.

"There's a huge difference between being a millionaire and a billionaire," Cuban told GQ. "After I sold my first company, I had like $2.5 million dollars in the bank [and] I still kept a budget. I still have that budget, actually."

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank," which features Mark Cuban as a panelist.

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