Jan. 3, 2021 10:00 am ET It is easy to spot bubbles. Too easy: They seem to be almost everywhere, almost all the time. Worse still for those of us who try to spot excess, much of the stuff that was labeled frothy in recent years went on to make big money in 2020 for those who bought into it anyway. The question for investors: Were the bubble calls just wrong? Or are we in a new era of wild speculation driven by cheap money that must inevitably come to an end? I lean toward the latter. But the stunning performance of so many bubble stocks this past year shows that even if this turns out to be right eventually, there is plenty of scope to be horribly wrong in the meantime.