People will buy anything if it’s marketed properly, and in the 1970s that is particularly true when Gary Dahl sold millions of Pet Rocks across America. He became a millionaire by selling rocks. Let that sink in for a second. Boxed up in something akin to a McDonald’s happy meal box, the Pet Rock was literally a smooth stone, nothing more. It was labeled “the perfect pet” and had a series of commands, including, “Play dead.” People loved it, seemingly forgetting that there was an endless supply of rocks sitting right outside their door.