Reid Hoffman, the cofounder of LinkedIn and a notable investor, told The New Yorker earlier this year he estimated that more than 50% of Silicon Valley billionaires had bought some level of "apocalypse insurance," like an underground bunker.

A new article in Forbes suggests the superrich are making significant land grabs in America's heartland, where the climate is mild and the locations are conducive to survivalism, farming, and living on the land. States like Colorado, Montana, Nebraska, New Mexico, North Dakota, Texas, and Wyoming are home to several fortified shelters and vacation homes where wealthy billionaires could happily live out their post-doomsday (or retirement) days.

According to Jim Dobson, a Forbes contributor, lots of billionaires have private planes "ready to depart at a moment's notice." They also own motorcycles, weaponry, and generators.

None of the billionaires named by Forbes has said publicly that their vast amounts of land would be used for apocalypse preparations — though they certainly would make good hideouts.