I've never had a Facebook account nor wanted one, and similar to something that's been said on this thread, I too feel disgusted at how many ways Facebook seems to be almost required by a lot of other things in life now, even down to some TV show only having Facebook as a way of responding or participating in something regarding the TV show.
I've run across some websites that demand you log in on your Facebook account. I just leave.
I also, as someone else said, don't like the data mining aspect. And I'm not paranoid ("my mother had me tested!"
) but I do have a feeling that there are sinister uses to social networking sites that most users aren't even aware of or care about, but perhaps they should.
Finally, again as has been mentioned, the narcissism is off putting, plus also the pointless minutiae involved in that. "Having my morning latte now!" Okay.....Twitter, the same thing.
The only thing I have is an old Myspace Music account I set up ten years ago for my songwriting. But when Myspace changed everything it felt really unusable and I get the impression nobody actually uses their MySpace anymore even while still keeping one! There isn't even a comment section, or if there is I can't find it anymore. So basically it's dead; I never bother updating mine, it's just there if I need to refer someone to my music, which happens like....never. 