Snapchat Co-founder Evan Spiegel, who on Wednesday announced his engagement with former Victoria's Secret model Miranda Kerr, is currently valued at $2.1 billion by Forbes. The 26-year-old is also one of the world's youngest self-made billionaires. Spiegel founded the image messaging and multimedia app Snapchat in 2011 with his Stanford University friends Bobby Murphy and Reggie Brown.