03 Mark Zuckerberg At age 19 , Mark Zuckerberg founded Facebook alongside bis college roommate and fellow Harvard University student Eduardo Saverin . Zuckerberg first became a billionaire at age 23 , making him one of the youngest self-made billionaires at the time . Fast forward to today and the Facebook boss has a net worth of around $ 71bn , making him the third richest technology billionaire in the world . Zuckerberg took Facebook public in 2012 and today he owns nearly 17 % of its stock . www . facebook . com