And now, he’s just revealed that being thrifty was one of the key drivers to building his first business. 

When a user online asked his best investment of all time, The Shark Tank star replied it was “living like a student long after college so that I could start my business.” 

It’s not the first time the Mavericks owner has admitted he penny-pinched his way to wealth. In his previous “Success and Motivation” blog series, Cuban shared his most frugal habits that shaped him into the business owner he is today. 

Some of those habits included driving $200 cars (one of which had a hole in the floorboard), sleeping on the “couch or floor” because he didn’t pay to have his own bedroom, and wearing one of two polyester suits he bought for job interviews—for a grand total of $99.

Today, Cuban has an estimated net worth of $6 billion and lives in a 24,000‑square-foot mansion in Dallas. But you won’t catch him wasting money on butlers or a chauffeur. The billionaire previously revealed he still does his own laundry, drives himself from A to B, and has regular friends he grew up with.. “I just try to be the same person as I was when I was poor and middle and rich,” he told The Really Good Podcast.

Fortune has reached out to Cuban for comment.

Cuban’s journey to success hasn’t ended. After selling his company Microsolutions at age 32 for $6 million. He then co-founded Broadcast.com, which he sold to Yahoo for over $5 billion in stock. He then began appearing on ABC’s Shark Tank in 2012 up until this year. Now, Cuban is focused on his prescription drug venture Cost Plus Drugs and co-owning the Dallas Mavericks. 

His secret to maintaining success is constantly learning. Even when he was in his 20s and hopping his way through jobs he thought were too “embarrassing” to put on his résumé, he viewed each one as an opportunity to learn.

“[I believed] that every job I took was really me getting paid to learn about a new industry. I spent as much time as I could, learning and reading everything about business I could get my hands on. I used to go into the library for hours and hours reading business books and magazines,” he previously wrote in one of his old blog posts. 

“I would get so involved with learning a new piece of software that I would forget to eat and look up at the clock thinking it was 6 or 7 p.m. and see that it was 1 a.m. or 2 a.m., time would fly by.” 

And now, Cuban wants Gen Z to have the same attitude towards learning AI. In March, he even rolled out a chatbot with MasterClass on Call so users can ask AI-Cuban for advice on emulating his success. 

“If I was 16, 18, 20, 21 starting today, I would spend every waking minute learning about AI,” Cuban said at SXSW earlier this year. “Even if I am sleeping, I am listening to podcasts talking about AI.”