The vast majority of the billionaires on this year’s Forbes list hail from these 10 sectors. : There are a record-smashing 2,755 billionaires in the world, according to Forbes’ 2021 World’s Billionaires list. How did they make their mega-fortunes? By doing everything from starting hedge funds and tech companies to breeding pigs and brewing kombucha. But certain industries offer a more common route to riches than others. The most likely way to make a billion-dollar fortune: go into finance and investments.