By Rafael Badziag

There are billions of people in the world, and only a tiny fraction of them are billionaires.

What distinguishes the billionaire’s thought process from everyone else’s? What are their secrets to achieving outrageous success? What are their belief systems? What gives them the energy to pursue ambitious goals?

To find the answers, I spent six years conducting face-to-face interviews with 21 self-made billionaires, anddocumented the principles that led them to great success in the book, “The Billion Dollar Secret.”

But throughout my journey, I learned something that I found deeply insightful: Just like the rest of us, billionaires have regrets.

Based on my conversations, here are some of the most common ones:

1. Not jumping on great opportunities

With great risks comes great rewards. But you’ll have a hard time reaping the rewards if you don’t take action fast. Many of the billionaires I spoke to learned this lesson the hard way.

Tim Draper, a venture capitalist and billionaire, is one of them. When asked what advice he had for people who would like to be as successful as he is, he answered: “Choose a goal and go after it.”

But even Draper has failed to act. He told me a story about when he first became interested in investing in Facebook. At the time, Sean Parker, who was president of the company, first said the company was valued at $20 million. But Draper got into a bidding war over the company that eventually went to a $115 million valuation.

Draper ended up backing out. That’s a regret, he said, because Facebook grew in value many times over.

His firm was also outbid when attempting to invest in Yahoo. “I should have just gone ahead and written the check with a note and let them convert it into whatever,” he said, of making the first offer on Yahoo. “When you spot a great opportunity, don’t hesitate.”

2. Not living in the present

Chip Wilson, founder of the athletic clothing company Lululemon, has a great mantra: Live in the present. But it took him a few years to get there.

When building his first sports apparel company, Westbeach Snowboard Ltd., Wilson said he found himself struggling until he made a life-changing realization.

“I was living my life in the past, in angst about things that I’d done in the past, or I was living my life in the future,” he said, adding that he was never fully appreciative of the people he was with or the things he accomplished in that moment.

“It seemed to me I was always in survival mode. I was always thinking, ‘What am I going to do in the future?’ I recognized that I spent probably 40 years of my life not saying, ‘Oh, isn’t life great?’”

As soon as Wilson changed his mindset, he started telling himself: “I live a great life.” And that helped him move forward by thinking about how he could become a better person and create a difference in the world.

3. Not starting soon enough

Despite their success, many billionaires regret not pursuing their goals earlier in life.

Peter Hargreaves is the founder of Hargreaves Lansdown, the largest financial services company in the UK. When asked what he would do differently if he could start his business all over again, he answered: “Well, I’d probably start sooner.”

I received a similar answer from Naveen Jain, who started his first company, InfoSpace, when he was in his late 30s. “I wish I had done it when I was in my 20s,” he said. “I would have 20 years more experience to be doing things.”

Why is that important? “Because you learn a lot more by doing it yourself than by learning from someone else,” he explained. “So if I had done it for 20 years, maybe my first company wouldn’t have been successful, and a second company wouldn’t have been successful…but a third company would have been.”

As Ron Sim, the Singaporean billionaire who built OSIM International, a maker of high-end massage chairs, told me: “There is never a right moment to start a business or have a child. But if you don’t do it, nothing will happen. So don’t wait for the right moment. The sooner you do it, the better.”

4. Not being bolder

Billionaires are also humans. They weren’t born the greatest risk-takers, defying all fears. I asked Jack Cowin, who founded Competitive Foods Australia (which operates Burger King’s Australian franchise as Hungry Jack’s), about what he would have done differently if he could go back to being 21.

“I’d be bolder. I’d take more risks,” he said. “The fear of failure makes you more conscious. The fear of debt makes you more conscious. So I would have more confidence in myself that I could find my way through the maze.”

However, it’s important to balance boldness with caution, he added. Otherwise, you’ll go broke. “If you make a mistake, you make a misjudgment. It’s easy to do.”

In the restaurant business, “you’re never that far away from the danger of someone dying from food poisoning or from someone making a mistake regarding procedures,” he explained. “Everything requires constant diligence. It’s a risk that you live with all the time, so you’ve really got to manage it properly.”

5. Not changing fast enough

Frank Hasenfratz, founder of automobile parts manufacturer Linamar, says, “Every day, you’ve got to change. If you don’t change, you die.”

Hasenfratz is well aware of the changing world and of the need to adapt to changing conditions.

To illustrate his point, Hasenfratz said he once checked a Chamber of Commerce document from 1964, when he started his own business. At the time, the documented listed about 100 manufacturing plants. But now, he said, almost all of them are gone.

“I’ve been here for 60 years,” he said. “And if you’re not a little bit apprehensive, if you don’t think, ‘I’ve got to do better tomorrow, I’ve got to get a different product or a more advanced product’ — if you don’t do that, you won’t be here for long.”

Mistakes and failures are necessary

Despite the many regrets that these billionaires have shared with me, what surprised me was how little they actually dwell on the things they didn’t do. In fact, almost all of them expressed that mistakes and failures are inevitable.

Cowin’s attitude is, “If you haven’t had a few failures, you haven’t tried enough. You’ve been lazy.”

So the lesson here is to avoid looking back at your actions in a disapproving way. Instead, focus on what you can do now to improve the future.

When it comes to regrets, Cowin said his basic make-up and attitude is a positive one. “If I was 21 again, there wouldn’t be too many things I’d do differently,” he told me. “Sometimes I might’ve gone harder on this or on that. But I think it’s important not to obsesses over the things that didn’t work.”

Rafael Badziag is an author and expert in the psychology of entrepreneurship. He has interviewed more than 21 self-made billionaires from all over the world to learn about their secrets to success. His new book, “The Billion Dollar Secret,” is an Amazon best-seller. Rafael has been featured on NBC, CBS, USA Today and The Wall Street Journal.

This article first appeared on CNBC https://www.cnbc.com/2019/09/04/5-biggest-life-regrets-of-self-made-billionaires.html and is republished with its permission.