I don't know if that has been empirically demonstrated, though, and it's a little like playing "musical chairs", because you don't benefit from the higher prices until you power down.

This is the point that I reflect on the most. But it does seem that, for the most part, it is a question of individual benefit that drives the Powering Up. That said, however, the fact that so many people Power Up long-term is something that gives us an advantage over other tokens, because most other PoS token have no other use than to gain interest, but then people get anxious and withdraw the stake because of insecurity, whereas most Steemian stake for the purpose of engaging the platform and therefore don't look at the price as much. Steemit incentivizes long-term holding beyond just APR.