I think a very large number of people don't even have SA (The ones who think they do)
It's just their there current lifestyle isn't the way they want themselves to be, you start thinking and looking at everyone else like where they are and what their doing. Because humans in general especially younger age are VERY influenced by other people to their mentality, and this is sort of the medias fault portraying crap like one tree hill and gossip girl. Because when you look around in the sun you see generally extroverts. But there are many, many introverts but they are the ones you don't notice and it makes it harder for you to cope with others.
I'm sorry if some of you might have real heavy anxiety, but I believe this disorder is just a excuse for most people and they make things a lot worse for themselves then they really are.