Facebook managed to beat out it's competitors to the top spot, and maintain that spot long enough to the point where it has just become a constant in people's minds now. Every other attempt to dethrone has been too technical minded I think. There was that Diaspora that gave users privacy, only to find people didn't care about that (the majority). Then there was Google+, who again introduced a whole lot of lingo and looked complicated to use and why bother? Everyone's on Facebook after all, and Google = Search, everything else is just riff raff!

Once you stop talking to developers and programmers, you find that people don't give a shit about things remotely technical, and just use stuff because 'everyone else is using it'.

Saying all that, these days my FB feed has gone advert mad, and I find I mainly use it for event organisation instead. I do get the feeling it is slowly dying though despite being profitable, but whether it will be replaced by a new social networking site, or a set of separate apps with specific functions instead, remains to be seen.