While the nickname Mr. Wonderful may sound like sarcastic jab at Kevin O'Leary's personality, the moniker couldn't be more accurate. The Shark Tank judge doles out harsh advice to hopeful entrepreneurs, but he does it with good intentions. 

"I'm trying to test the mettle of those entrepreneurs, because if they think it's tough in the Shark Tank, wait until they get out in the real world," O'Leary told Business Insider. "If they can't take a guy like me, then they're not ready."

O'Leary, who is speaking at the iCONIC event in Austin on Dec. 6, told Boston Magazine that Barbara Corcoran coined his nickname during the first season when he attempted to negotiate a difficult deal. "Barbara said, 'Well aren't you Mr. Wonderful?' and I said, 'You know what Barbara, I am!'"

O'Leary's harsh demeanor has been a Shark Tank staple for nine seasons. He'll often tell entrepreneurs to kill businesses that he doesn't believe will survive and start something new. For example, in the most recent season of Shark Tank, the judges heard a pitch for the Christmas Tree Hugger, a wrap that goes around the trunk of a fake Christmas tree. Founder Ryan Kenny had decent sales figures and showed initiative by cold-calling companies like the supermarket chain Kroger to get his products on its shelves. But when Kenny admitted that Kroger wasn't planning on re-ordering Christmas Tree Hugger after only 40 percent of units were sold, O'Leary shared his opinion on the startup.

"I don't want to offer you any encouragement," O'Leary said on the show. "I want to tell you to take this behind the barn and shoot it, so that it leaves time for you to do something else. This product is a dog."

O'Leary made a name for himself after launching Softkey Software Products in 1983. He built the business in his basement and sold it in 1999 to Mattel Toy Company for $3.7 billion. Shortly after, he started his mutual fund company O'Leary Funds and has since launched O'Leary Fine Wines and the O'Leary Financial Group.

"Maybe people think I'm bullying them. That's not true," O'Leary told Business Insider. "I'm the only guy there who tells the truth all the time. I don't care about your feelings; I care about your money."