It's possible to become a billionaire, but it's not easy. Even if you could invest a whopping $50,000 per year in the stock market for 25 years and earn an average annual return of 10%, you'll end up with less than $6 million. If you turn out to be an incredibly savvy (or incredibly lucky) investor and you average annual gains of 30% (which, by the way, would outpace even Warren Buffett's 50-year average with his Berkshire Hathaway company), you'd end up with only about $150 million.
Still, it's possible to become a billionaire -- perhaps if you start a very successful company. Activision Blizzard, for example, is buying King Digital Entertainment, maker of the Candy Crush game, for almost $6 billion. King Digital traces its roots back to just 2003. Great fortunes can be built in a relatively short time.
Here's a bit more guidance: Per the UBS/PwC 2015 Billionaire Report, there are three personality traits common in billionaires that are key to entrepreneurial success:
Smart risk-taking: Many of us don't have this quality. We take on a lot risk, by taking chances on penny stocks or by chasing overpriced high-flying stocks or buying lottery tickets. Instead, we need to embrace rational risk, where there's a decent chance of success. We might reduce risk, too, by seeking undervalued investments that offer greater margins of safety.