Chill winds have been battering America’s eastern seaboard for weeks, driving temperatures in places to their lowest in decades. But that has nothing on the deep freeze into which investors have shoved crypto assets. The value of a bitcoin has dropped from $124,000 in early October to around $70,000 today, and the market value of all cryptocurrencies has fallen by more than $2trn. Though the asset class has slumped before, its boosters now seem more despondent than ever.