The world's 20 youngest billionaires are evidence that enormous fortunes can be created in far less than a lifetime. All of them are under 40. The youngest, Dustin Moskovitz, is just eight days younger than his Facebook cofounder Mark Zuckerberg (both are 26). The oldest in this group, Google cofounder Sergey Brin (age 37), is also the group's richest, boasting a net worth of $19.8 billion. All ages are as of March 28, 201
