30 Inventions That Seem Useless But Made Their Creators Millions

20. Pet Rocks

In 1975, a new toy debuted that puts all toys, before and after, to shame, for its alarming mediocrity yet incredible success level. This was none other than the pet rock. It was literally a small, smooth rock that came inside a cardboard box on a soft bed of hay. And it was supposedly a pet.

And lots of people bought it. Within the first six months of its debut, five million people had bought pet rocks for the price of $3.95 each. In 1975, $3.95 was worth a lot more than it is today. Were people just more gullible back then? Had they had one too many LSD doses when they bought their pet rock? Maybe. But you have to hand the creator props for what was an incredibly successful marketing campaign. He became a millionaire by selling people rocks inside cardboard boxes.