Elon Musk's fortune has more than tripled in the past year, clocking in at $2.7 billion for 2013. Stock in Tesla Motors, the electric carmaker he founded, is up 625% in the past year, and stock in SolarCity, the solar panel designer and installer run by his cousin Lyndon Rive, is up 340%. His privately-held spacecraft-maker SpaceX was reportedly valued at upward of $4 billion in March 2013. In February, Tesla announced a $5 billion plan ($2 billion from Tesla, $3 billion from partners) to construct a new factory focused on large-scale battery production. Born in South Africa, by age 12 the serial entrepreneur had sold computer code to a space game for about $500. Musk left for the U.S. at 17 and made his first fortune as a co-founder of PayPal.
