Sure, working hard, being smart, overcoming failure and breaking convention can all play a role. But lots of people do those things and never get rich.

There is no shortage of hypesters and hucksters offering the "secret" to getting rich. The reality is that all kinds of people get rich in all kinds of ways, most of them involving being the right person in the right place at the right time.

Yet billionaires often share common attributes. And one of those traits is eloquently explained by Justine Musk, the ex-wife of billionaire inventor Elon Musk.

In a piece in Quora, Justine Musk said that "extreme success results from an extreme personality," and that billionaires like Elon Musk or Bill Gates "tend to be freaks and misfits" who developed extreme strategies for survival as kids and later applied those strategies to business.

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But their chief characteristic can be summed up in two words: "Be obsessed."

"If you're not obsessed, then stop what you're doing and find whatever does obsess you," she said. "It helps to have an ego, but you must be in service to something bigger if you are to inspire the people you need to help you (and make no mistake, you will need them)."

She said that people who are obsessed with a problem or issue can work through all the distractions and barriers that life puts in their way. And that obsession needs to be your own, to the point where it borders on insanity.

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"Extreme success is not like other kinds of success; what has worked for someone else, probably won't work for you," she wrote.