Young Money: Billionaires Under 40 Even though his net worth is $17.5 billion, Mark Zuckerberg, the founder and CEO of Facebook Inc., still gives presentations in t-shirts and jeans. In 2011, The Economist named the 27-year-old New York native the world's wealthiest person, when adjusted for age. Zuckerberg has control of 56.9 percent of Facebook's total pre-IPO voting power, according to Forbes. David Paul Morris/Bloomberg/Getty Images