The story of Bill Gates' success is legendary. Gates, who began programming computers at age 13, started Microsoft, with his childhood friend Paul Allen, at age 20.
He quit Harvard during his junior year to devote his energy to his software outfit; and for the past 17 years has reigned as the richest person in America.
Warren Buffett, the second-richest American, got started on his path to wealth even earlier, reading all the investment books at his Omaha library by age 12. He started his first investment partnership at age 25.
Gates and Buffett lead the 272 self-made billionaires on our list of Richest Americans. These moguls have amassed a combined fortune of nearly $920 billion. The top 20 richest entrepreneurs, including well-known tech executives like Oracle's Larry Ellison, Google
)'s Sergey Brin and Larry Page, and Amazon's Jeff Bezos, account for more than a third of that wealth. Forbes 400 members who inherited their wealth are worth just $450 billion, less than half as much as their self-made counterparts.
But for every Gates and Buffett who makes a billion dollars, there are hordes of earnest entrepreneurs around the country taking risks, starting businesses and trying desperately to make fortunes. So what pushed these wealthy moguls to the highest levels of success, and what keeps them going strong?
In Bill Gates' instance, committing to something early and moving quickly helped. The richest man in America explains on Gates Notes his decision to drop out of college and join Allen: "We were afraid if we waited, someone else would beat us to it."
Buffett says it's emotional stability. "When you come to a conclusion, you have to really not care what other people say," the Oracle of Omaha told Steve Forbes in September.
America's richest politician Michael Bloomberg was motivated by a personal setback. He was fired from Salomon Brothers in 1981 but walked out with a $10 million payout. Rather than licking his wounds, retiring or trying to get a job at another firm, Bloomberg took a risk and started his data firm one day after he walked out of Salomon for good.
"Living well is the best revenge," he recently said of his multibillion-dollar turnaround in a presentation to Dartmouth students.
These super wealthy entrepreneurs also keep going long after they've made fortunes, setbacks be damned. Casino mogul Sheldon Adelson, once the third-richest American, lost $22 billion in 12 months, or 88% of his wealth during the recession. His net worth fell from $28 billion in 2007 to just over $3 billion in March 2009. At one point he personally injected $1 billion of his own cash into Las Vegas Sands
) to help make a debt payment and keep the company afloat. Today he's once again one of the country's most successful entrepreneurs, worth $14.7 billion, as shares of his gaming outfit have surged more than 1,500% from their low. Adelson is determined to keep the rally going. He told Forbes earlier this year: "I'm too old to be a kid, so call me the 'comeback adolescent.'"
Sometimes even the billionaires aren't quite sure how they got so wealthy. In his letter accepting Bill Gates and Warren Buffett's Giving Pledge, oil tycoon George Kaiser, the country's 18th-richest self-made billionaire, wrote: "I recognized early on, that my good fortune was not due to superior personal character or initiative so much as it was to dumb luck."
When pressed by Forbes recently as to what important decisions led to his success aside from luck and circumstance, he admitted that he had the good judgment to enter the oil business before the Arab embargo, the banking business during the collapse of all Southwest banks and the private-equity business during market downturns. "So I'll claim timing, which is probably another word for luck and circumstances.
We should all be so lucky.