TrendingPeopleFunnyIn 2009, Brian Acton applied to work at Facebook and was rejected. He also applied to Twitter and was turned down. He tweeted about both rejections. Then he co-founded WhatsApp with Jan Koum. In 2014, Facebook bought WhatsApp for approximately $19 billion — making Acton a billionaire and turning his rejection into one of the most expensive hiring mistakes in corporate history.8 days ago