But "Mr. Wonderful" recently went to Harvard Business School to hear pitches from MBA candidates and to offer his best advice on how to get financial backing from investors.
CNBC followed O'Leary into the classroom where he talked about the "three attributes that are found 100 percent of the time in every pitch that actually gets funded."
Entrepreneurs must be able to "articulate the opportunity in 90 seconds or less," O'Leary said. "Your communication skills to explain the opportunity have to be crystal clear."
O'Leary said investors like himself always want to know "what gives you the credibility to actually take a great idea and execute on it."
"There's only a first time, once, that you're going to hear [a pitch]. And that's where the magic happens," he said.
"Here's the killer," according to O'Leary. "You have to know your numbers. How big is the market? How fast is it growing? How many competitors are there? What's the breakeven analysis?"
Of the pitches from a number of Harvard MBA candidates, O'Leary told CNBC's "Squawk Box" this week, he's seriously looking into a couple of them.
O'Leary said he also warned the students about "the real world," by telling them about an experience he had.
"When I was their age ... a guy like me walked in and said, 'You guys have no idea in terms of what's going to happen. You think you're sitting here and you're so smart,'" he said. "I remember looking down at him and saying, 'What a beep this guy is.'"
"His whole point was experience is worth 10 times an MBA," O'Leary recalled. "I thought he was such an arrogant 'you know what.' [But] he was 100 percent right. And that is the lesson I try to impart on these students."
"Don't assume anything until you get outside and see what the real world is going to do," he stressed. "The real world is a nasty, nasty place."
Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."