Tech billionaire Mark Cuban hasn't always been rich. He grew up in a working class family in Pittsburgh, and after he graduated from Indiana University in 1981, he got a job at a retail software company, "Your Business Software."
"I sold software and I got fired," says Cuban, in conversation with Arianna Huffington on The Thrive Global Podcast.
Cuban will never forget the boss who fired him, because the man taught him exactly how he did not want to lead. As Huffington put it, he was a "reverse mentor."
"I got fired because he wanted me to open up the store. It was a software retail store — I had to sweep the floor, make sure the windows were clean, make sure the store was open on time — and I had a big deal I wanted to close. And I thought, 'Okay, I'm gonna let Michael (his name was Michael) know that I've got everything taken care of, someone's watching my shift if you will, and I'm gonna go pick up a $10,000 check.'
"I figured when I came back he'd be thrilled to death, right? Fired me on the spot," says Cuban.
Not only was Cuban fired for showing initiative and bringing revenue into the company, but Cuban also remembers being chastised by his boss for not being well-dressed.
"Literally back then I was buying clothes from a used clothing store, because they had used polos that they would redo, and my suits were two-for-$99 polyester suits. You didn't have to dry-clean them, you just ran through the rain a few times," says Cuban.
"And I remember him saying, 'Well, you need to dress up and this is where you can buy some nice suits.'"
The boss cared more about how Cuban looked than revenue he was bringing in. That, says Cuban, is a death knell for a company.
"He was more interested in the show, and he would never go on sales calls," says Cuban.
"And it was there I learned that sales cures all — there's never been a company that succeeded without sales.
"Just time after time ... the companies I worked for that didn't do well, they didn't focus on the results that mattered to the business," says Cuban. "They focused on how well they looked and the show" instead of the bottom line.
Looking back, Cuban says he is glad he had that experience. "I'm glad I learned those lessons early," says Cuban.
Now the tech billionaire entrepreneur and star of ABC's "Shark Tank" encourages people right out of college to get into the workplace and learn as much as they can on the job.
"Kids who are graduating today, they ask about jobs and things they should do and everything, and I always like to tell them, you don't have to get the perfect job. When you're 22, 23, 24, there's no such thing as failure, really," says Cuban.
"Whatever job you take you're getting paid to learn. And you just spend however many years paying to go to school, and you paid a lot of money, probably still owe money — take that job. You're gonna get paid to learn, and if it was like my experience where I learned what not to do and I was getting paid, it was still well worth it."
Disclaimer: CNBC owns the exclusive off-network cable rights to "Shark Tank."