The prepper billionaires of Silicon Valley

Think back to Y2K. Remember the people who stocked up with years of food, water and supplies? Those doomsday preppers have long been the object of ridicule, but now Silicon Valley billionaires are joining their ranks. <p>Learn more about your ad choices. Visit <a href= "https://megaphone.fm/adchoices">megaphone.fm/adchoices</a></p>