This story is part of CNBC Make It's The Moment series, where highly successful people reveal the critical moment that changed the trajectory of their lives and careers, discussing what drove them to make the leap into the unknown.

Todd Graves knows how lucky he is to still have a business at all.

His chicken finger restaurant chain Raising Cane's brought in $3.7 billion in net sales last year, contributing significantly to his estimated net worth of $9.5 billion. But nearly two decades ago, Hurricane Katrina almost wiped away the entire company — a position Graves was only in due to his own self-proclaimed "stupid financial strategy," he tells CNBC Make It.

Graves, now 52, co-founded the first Raising Cane's location near LSU in 1996. By 2005, the chain had 28 locations across Graves' home state of Louisiana, bringing in an annual revenue of $54 million, according to a company spokesperson.

To achieve that growth, Graves racked up debt. He took out loans with private investors at a 15% interest rate, and used that debt to secure larger loans from banks who treated it like equity, he says.

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When Katrina hit the New Orleans area in 2005, massive flooding shut down thousands of businesses across the state, including 21 Raising Cane's locations. With little revenue coming in, Graves faced a stark reality: He might not have enough money left to cover wages and avoid defaulting on his loans without selling his equity in the company.

Instead, Graves built a plan to open restaurant doors as soon as power returned to the region. He gathered employees from less-affected areas to organize cleanup efforts, get supplies to his flooded stores and learn to cook and serve food under a boil-water notice.

Raising Cane's reopened its first shuttered location in just two weeks, and got a sales boost from being one of the only restaurants available to locals, says Graves. With cash flowing again, Graves made his payments and avoided selling any company equity, he says. Today, he still owns 90% of his business, according to Forbes.

Here, Graves discusses the panic he felt as he watched New Orleans' levees break, what he learned about handling crises of any kind and how to avoid the same financial mistakes he made.

CNBC Make It: When Hurricane Katrina closed the majority of your restaurants, how dire was your financial situation?

Graves: I remember watching on television from our location on Lee Drive [in Baton Rouge, Louisiana] when the levees broke. I knew I had leveraged the business. Twenty-one of those restaurants were closed down. There were no more sales coming in. I still had to pay my bills.

I gathered the team, explained it all to them and said, "I'm sorry I put us in this bind." I also said, "Our crew members need jobs. We also need to be open for the communities. People need a hot meal when they're redoing their houses, right? And we need to save the company. We're in a bad financial situation, so we need to get after it."

We worked with the health board. We worked with the state. Tyson Foods delivered chicken to the back of our office, because they couldn't get into [the most damaged areas of New Orleans] and do their own logistics.

We were big enough to have a big crew to help. And then we just worked ourselves to death.

What was the worst-case scenario, in your mind?

While we're doing all of the planning, we're talking to all our vendors, all our banks. Everybody was super nice, but they wouldn't commit to extensions. They were just like, "We'll just see how it goes."

I could've gone back and offered equity, but I didn't want to say, "Hey, I screwed up with your money" — even though they knew, [because] I showed them everything. And I just did not want to [give up] equity. The reason why I own so much of my company, versus some other people, is: I was very risk tolerant. Risk did not bother me at all.

If you believe in your business, be very careful selling equity. You're going to work just as hard [as you would if you'd retained full ownership].

What did you learn about how to handle a crisis of any kind? If someone is worried they could lose everything, what should they do first?

You can say, "This is an amazing challenge, and we're going to beat it. We're going to figure it out." Or, you can watch the news and see how devastating [the storm is], and how business is going to struggle. If you listen to that negative thought, your brain starts to believe it.

When you hit adversity, you have to believe you will get through it. That's the most important part.

Then, you have to plan. [Lay out] the big challenges in front of you — we like a whiteboard — and be completely transparent about the situation you're in.

You build a plan and go after it with relentless pursuit. Trust your team. Work with your team. It changes 1,000 times, your plan. Keep doing it and you can pull through.

Did nearly losing your business change your definition of success? What do you consider "successful" now?

At first, my American dream was: You can go out and start your own business, and you can make the business work, and that's a success.

Now, my American dream is: You can start your own business and you can do right by people. Bring people into a great place to work that's a great place to grow. They learn values they take to other companies. The business generates income, including profits that you can use [philanthropically] in a really, really big way.

We've given [more than $140 million to community organizations across the U.S. since 1996]. I can't wait to give $150 million in a year, God willing.

You can become successful enough to help others become a success, and others to be happy. That's the American dream to me.

The debt-financing strategy that got you into trouble is a relatively common one. What's your advice for anyone tempted to try it?

I was young. I thought I was 10 feet tall and bulletproof. We had no problems with anything financial [up to] this point. I [didn't imagine] a natural disaster or anything like that happening. I was like, "Someday we'll catch up, and I'll be able to use my own dollars instead of these sub-debt investments."

The stupid financial strategy was over-leveraging myself [and] not having safety cash. Now, I have a stockpile of personal safety cash in case something goes wrong, because things generally do.

Don't get yourself a bad financial bind. Just slow down [your company's] growth. You'll get to a point, if you're successful, where you can really grow and you'll have your own money [to] finance the business.

This interview has been edited and condensed for clarity.

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