in financial markets if you reach the point where everyone knows something, then the exact opposite is usually about to occur.
Right because when everyone bought the google IPO because they knew it was an amazing company, it failed instead.
Did people sell their houses and put all the proceeds into google shares? I think you're misunderstanding the degree of conviction I'm conveying here that occurs in people's minds at major tops... i.e. contrarianism only works at the very extremes of psychology