You've read it and heard it dozens of times: You can't have spectacular success unless you're willing to take some big risks. The thing about risks is, they don't always work out well. Sometimes they work out really, really badly--and that's OK. You can have a great big failure, lose almost everything, and still come back to conquer the world. You don't have to take my word for it, just look at the careers of some of the planet's wealthiest people.

A couple of weeks ago, the personal finance site GOBankingRates published a piece on the "21 Habits of Highly Successful Billionaires." It's a great piece, and there are lessons in it for all of us. But I was struck by how many of the billionaires' histories included things like dropping out of college, changing careers, losing nearly all of their money, and getting fired.

There's no better way to confirm that failure is an important part of growth than to take a look at the lives of some of these business superstars:

1. Richard Branson's mother had to re-mortgage her house.

Branson was dyslexic and had poor academic performance. On his last day at Stowe School in Buckinghamshire, the headmaster told him he would either wind up in jail or a millionaire. It was very nearly the former.

Branson began his Virgin line of record shops out of frustration with the high-priced record stores then prominent. But selling records in England at that time meant adhering to stringent rules about discounting and tax payments. In 1971, Branson was questioned for selling records in Virgin stores that were supposed to be for export. He avoided going to trial by agreeing to pay back taxes plus a fine. His mother re-mortgaged the family home so he could make the payment. They had the last laugh, though. According to Forbes, Branson is now worth about $4.9 billion.

2. Mark Cuban got fired from his first sales job.

Fresh out of Indiana University's business school--which he picked, sight unseen, because it was the cheapest in the top 10--Cuban got a sales job at Your Business Software, the first retail software store in Dallas. He knew little about software initially but spent his evenings reading manuals to bone up. He also learned how to install and configure programs on the store's computers and was soon going out as a consultant, doing installations for the store's customers and splitting the fee with his employer.

That's where the trouble began. One day, a client called and asked Cuban to come to his office at 9 a.m. to close a deal. Cuban was supposed to be opening the store at that time. In retrospect, he writes in his blog, "I guess I could have rescheduled the appointment, but I rationalized that you never turn your back on a closed deal." So he called a co-worker to open for him instead. He arrived at the office the following day, bringing a check from the customer--and was promptly fired. Today, he has a net worth of about $3 billion and owns the Dallas Mavericks.

3. Sheldon Adelson lost 90 percent of his net worth.

The CEO of the Las Vegas Sands Corporation reportedly twice made a fortune by his 30s--and lost it both times. But Adelson suffered even bigger losses as the financial crisis battered his casino businesses, and in 2009, his net worth dropped from $28 billion to $3 billion, as Sands went into massive debt to pay for its ill-timed 2007 expansion.

Now $3 billion may seem like quite enough to you and me. I at least would have been tempted to cut my losses and get out of the business while I could. But Adelson poured some of his personal funds into Sands to keep it afloat. That risk paid off. When the economy bounced back, the value of Sands stock climbed 7,000 percent over five years. Today, his net worth is estimated at more than $30 billion.

4. Larry Ellison nearly bankrupted Oracle.

In its early days, Oracle's sales team apparently overstated revenues to boost their commissions. The company had to restate its earnings--twice--and its market capitalization dropped by 80 percent. Four years after its IPO, Oracle appeared on the verge of bankruptcy. It took massive lawsuits and replacing some of the senior staff with more professional managers to get the company back on an even keel. Ellison called releasing wrong earnings statements "an incredible business mistake."

Both he and Oracle have recovered nicely. Now, Ellison is the fifth richest person in the world, with a net worth of around $56 billion.

5. Charlie Ergen was ejected from Las Vegas.

The co-founder of Dish Network was a professional gambler in 1980. He and his buddy Jim DeFranco tried playing poker and blackjack in Vegas, but they were accused of counting cards and thrown out of town. As they wondered what to do next, they saw a truck drive by with a huge satellite TV dish on it. They decided to gamble on that business for a while instead. The rest is history. Ergen's net worth is now over $15 billion.