Another root cause:

"I started to compare my life to others, hating people based off of their status. All it brought me was anger and a lower self-confidence. Almost immediately after deleting it, I felt better. I'm mostly ok with how I live my life and I don't need to compare my life to that of others."

via http://www.reddit.com/r/AskReddit/comments/11wm5w/to_those_w...