Richard Branson doesn't want to be defined by his money.

Specifically, he finds it "quite insulting" when he is introduced as "the billionaire Richard Branson," rather than as the co-founder of Virgin Group, he tells CNBC Make It. The reason: Nobody should view their net worth as an ultimate measure of success, and it's "very sad" when making money is the sole focus of a person's life, he says.

"Maybe in America, 'billionaire' is a sign of success, but that rankles me," says Branson. "I think that your reputation is what you create."

In Branson's case, his reputation is often defined by Virgin Group, a venture capital and holding company that owns businesses in a wide variety of industries, from airlines and telecommunications to spaceflight.

The company is largely responsible for his estimated net worth of $2.5 billion, according to Forbes — but he chafes at the idea he created it to make money.

"Your reputation is [whether] your team of people who work with you are proud of what they've created," Branson says. "Paying the bills at the end of the year is important, but what entrepreneurs are doing all over the world today — and the only reason they're succeeding — is that they're making a difference in other people's lives. And that's all that really matters."

Whenever Branson launches a new venture — citing Virgin Atlantic in 1984 and Virgin Mobile in 1999 — he asks himself two questions, he says:

• If I create this, can it be better than what everybody else is doing?
• Can it make a real difference in the world?

Financial success has often followed, but Branson is adamant that money has never been his chief motivating force.

His first successful business venture, a youth culture magazine called "Student," was primarily meant to challenge "stale" traditional publications, Branson has noted. It tackled cultural issues like popular music and campaigning against the Vietnam War.

"I wanted it to survive. And yes, I wanted to have enough advertising to pay the printers and the paper manufacturers," he says. "But money was certainly not the motivation for running a magazine."

Branson's top advice for becoming successful

Branson's advice: Seek out opportunities you find interesting and exciting. It's a recipe for greater happiness, and you're more likely to end up successful than if you're only thinking about the bottom line, he says.

"We only have one life," says Branson. "We spend a lot of time at work and it'd be sad if we're only doing it for our paychecks."

Of course, success is never guaranteed. If you do follow your passions, you'll still need factors like talent and perseverance on your side to avoid falling flat, experts say.

But Branson isn't the only billionaire who advises that personal fulfillment doesn't always have to come from amassing great wealth.

"Success isn't necessarily how much money you have," serial entrepreneur and investor Mark Cuban told LinkedIn's "The Path" podcast last year. "Success is just setting a goal and being able to wake up every morning feeling really good about what you've accomplished."

Cuban, who grew up in a blue-collar family near Pittsburgh, has long held that his career path was dictated more by a desire to control his own time than any financial aspirations.

"Time is the one asset you can never get back. You can never truly own [it]," he said at SXSW in March. "I wanted to be ... in a position where I get to call my own shots [and] spend time the way I wanted to spend time. That was always my motivating factor."

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