More than half of respondents believed bitcoin was in a bubble when it was trading at $2,200. A few months later, bitcoin had more than doubled and was trading at $5,300, but fewer people now believed they were witnessing a bubble. Photograph: Sascha  Steinbach/EPA

As US markets raced higher in January, ordinary investors were going gaga for stocks. There were four times as many bulls as bears, according to an Am(...)