When it happened, his mother imparted a few words of wisdom about parents teaching their children the value of work. "My mother said to me, 'The dead bird under the nest is the one that never learned how to fly,'" O'Leary tells CNBC Make It.
"Mom, that is a great poem, but I need some money," he says he replied.
But his days living on her dime were over. "You're not going to get any, so you're going to fly or you're going to be dead bird," she answered.
"Woah, no dead bird for me," O'Leary decided.
Today he presides over a multitude of companies bearing his last name: wine business O'Leary Fine Wines, financial company O'Shares Investments and private equity firm O'Leary Ventures. He's also famous as a judge on ABC's "Shark Tank," through which he's invested in businesses like Plated — a meal delivery company that sold to Albertson's for $300 million. O'Leary says it was the largest exit in the history of the show.
"I told them when they finished college, I was going to give them this: nothing," he explains. "Because that is what my mother did to me.
"You have to go make it on your own, and I think that is a very important lesson," he says. "I paid for birth through last day of college and then nothing." And, his tough love lessons don't stop there.
When his son Trevor was a teenager, O'Leary made him fly in coach on a trip to Europe while he flew first class, Business Insider points out.
"At 16, my son is making the connection between money and personal freedom," O'Leary writes in his book "Cold Hard Truth on Family, Kids and Money."
"I think that's the greatest gift I've ever given him: to help him see that connection. And I constantly reinforce it by doing Mean Dad things like making him sit in those crappy economy seats."
And when his kids were young, O'Leary's principles were the same.
"I'm in favor of allowance for children if they work for it, because then they equate the value of money to time worked," O'Leary explains. "I'm not in favor of just giving the money as if it grows on trees — because it doesn't."
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