Maybe. But the alternative hypothesis we have to evaluate against is that people don't expect Bitcoin to be good money in the first place, and their investments

Maybe. But the alternative hypothesis we have to evaluate against is that people don't expect Bitcoin to be good money in the first place, and their investments are driven by a desire to be part of the movement or a hope that they'll be able to get rich off of it. A sudden spike and then fall in Dogecoin, which was never intended to be taken seriously, is a pretty strong pointer in that direction.