Vanity Fair pegged Musk's net worth at $12.9 billion, thanks in part to Tesla's stock climbing up about 70 percent in the past year (despite a recent dip) and has surged by a factor of 16 since the initial public offering in 2010. It also can't hurt that Tesla scored about $1.2 billion in government incentives when it agreed earlier this month to build its gigafactory in Nevada. Additionally, Vanity Fair feted Musk for his involvement in both space-exploration company SpaceX and home solar-panel provider SolarCity and described Musk's marital status as "complicated." VF just loves that stuff.
Perhaps most impressive is the fact that Musk was the only auto executive to end up on either the publication's "disrupters" list or its "powers that be" list. The latter was headed by Fox's Rupert Murdoch, Walt Disney's Bog Iger and Comcast's Brian Roberts and Steve Burke. You can read Vanity Fair's write-up of Musk here.