Facebook used to be cool before they started screwing it up. I don't think it's users are stupid. I think they are wising up.
It has everyone, because.. well it has everyone. And once it got everyone, it started to change for the worse. The changes are what people are complaining about.
If there was an alternative with better privacy regulations and less crap, I think lots of people would jump ship. The problem is, most of the value of Facebook comes from the size of it's user base. In order for the alternative to be appealing, my friends have to have it.
Seasoned users are getting sick of Facebook, and the growth rate will eventually peak and decline if it has not already. It's going to take a while, but I think these days mark the beginning of the end for the Mark and the gang. Wait till the movie comes out.