I think the big stumbling block is that Facebook's growth is getting population limited I know some people who use Facebook once or twice an hour while others

I think the big stumbling block is that Facebook's growth is getting population limited I know some people who use Facebook once or twice an hour while others use it once or twice a year. Both of those users are counted the same when people talk about being population-limited. There's still room for growth, although I'm not about to claim that they are overvalued.