The madness of crowds

摘要

"BE MORE BRENDA," said the ads for CoinCorner, a cryptocurrency exchange. They appeared on London's Underground last summer, featuring a cheery pensioner who had, apparently, bought Bitcoins in just ten minutes. It was bad advice. Six months earlier a single Bitcoin cost just under $20,000. By the time the ads appeared, its value had fallen to $7,000. These days, it is just $4,025 (see chart).