we don't know that the price is "way too high" -- that is, to quote The Big Short what "makes it a bubble."

Regardless, we can only establish that in hindsight.

and efficient, in the efficient-market hypothesis framework here means something like "the globally, best guess, of current/publically available information about the future."

= point being: there's no model/idea/conviction/belief that provides an improved pricing compared to it.

(Maybe there's a relevant MONEY CLASS in here for the Stackers... who knows)