Facebook is weird. It's like a place where people can gaze at themselves and it's ultimately rewarded. I think it was Carlin who said modern society was nothing but a bunch of narcissists. Dude was onto something.
I think it's like anything else really. Communication makes it easier to avoid the pain of real life confrontation.
People stalking their exes of facebook. "ohh she got fat, hahaa. good" or "fuckk. im depressed. she is dating a 6'8 african american NFL star".
But in either case, FB is just "grass is greener on the other side". It's so easy to look at peoples profiles and how their best photos are up and how all their accomplishments and friends acknowledgements and fun activities are shared. Sure some people make negative status updates about stuff, but you will see lots of people who cherry pick what they want others to see.
But at the end of the day, most of us, probably have more in common as far as pain, guilt, depressive bouts, anexiety, failures, fear, jealousy and all that other stuff, than we realize.
We just naturally go to some on our friends list and you see their hot girlfriend, were they took their awesome degree, their awesome workout pictures, how their status updates got over 50 comments and people posting on their walls.
If you think like that it becomes easy to compare yourself. And then you feel shitty. Even if you know FB doesn't matter and even if everyone knows that FB friends dont compare to RL socialization it somehow seems to rub off on us.