“In life, only a third of people can become successful entrepreneurs. That’s it,” O’Leary said recently on the Diary of a CEO podcast. “And the rest can be very successful employees. And there’s nothing wrong with that—you can have a fantastic life.”

“You won’t be shackled to the ups and downs of entrepreneurship, the challenge of it, how hard it is. But you’ll never be free. And that’s the debate: Do you want personal freedom? It’s the only path.”

The 70-year-old software mogul knows a thing or two about building billion-dollar businesses. Founding SoftKey Software Products in the basement of his Toronto pad in 1983, O’Leary led the company to become a global education giant, aggressively acquiring competitors and working for technology greats like Steve Jobs. By 1999, he sold the company to Mattel for $3.7 billion; and is now known for being a no-nonsense investor on hit TV series Shark Tank. 

The pursuit of entrepreneurship isn’t for money—it’s for freedom

Despite his nationwide fame as “Mr. Wonderful,” O’Leary doesn’t think everyone can replicate his success—nor do they want to. 

Even now, as he’s teaching students at Harvard University, he said he witnesses a divide between the premier business students who want to become successful entrepreneurs, and those who will wind up as a cog working for massive corporations. 

“Two-thirds of [my students] want to become consultants…and lead a life of mediocrity, and never make a decision of consequence in their lives. And after 24 months, they are tainted with that disease forever,” O’Leary continued on the podcast. “They’ll always be good consultants, but they will never achieve greatness in any way.”

There’s a lot of money in entrepreneurship—with O’Leary himself boasting a net worth of around $400 million—and premier consulting jobs can also offer salaries in the high six figures. While the payoff is much higher in selling billion-dollar businesses, the serial investor insists that building companies isn’t about getting rich quick. You might have to sacrifice weekends off, but the independence that comes with it makes it worthwhile. 

“I’ve always said it’s not about the pursuit of money. It’s not about the pursuit of greed. You will fail if you do that,” O’Leary said. “It’s the undying love of freedom.”

Fortune reached out to O’Leary for comment.

The one trait successful entrepreneurs have

For the one-third of people who do go on to become entrepreneurs, O’Leary says the best of the best all have one quality in common: They can tune out the “noise” of their personal lives, to get the day’s three to five most important things done straight away.

“This signal-to-noise ratio to be successful, for Steve Jobs, 80/20—80 signal, 20 noise,” O’Leary explained. “If you go back in history, you’re going to find out that the geniuses of their time were close to 100% signal.”

It’s something he saw not only in his former business partner Jobs, but also in Elon Musk.

“Elon Musk, he has no noise. He does not deal with noise,” O’Leary said. “60 seconds of every minute, 60 minutes of every hour, the 18 hours he’s awake, it’s all signal. And look what he’s achieved.”

Other successful entrepreneurs recognize different ingredients for success. O’Leary’s former Shark Tank cohost Mark Cuban echoed that there’s one trait he sees in successful people: a strong work ethic. Tennis icon Serena Williams similarly believes that people need to grind “every day,” and be “very disciplined” to get to the top. 

Meanwhile, venture capitalist mogul Marc Andreessen believes that successful people can’t turn off their desire to grow their companies. It’s a star quality the billionaire Netscape founder said “very few” embody—with Tesla founder Elon Musk being an exception. 

“There is this decision that people have to make, which is, ‘Okay, if I have the latent capability to do this, is this actually what I want to spend my life doing?’” Andreessen said in an episode of the Huberman Lab podcast in 2023. “‘And do I want to go through the stress and the pain and the trauma and the anxiety and the risk of failure?’”