Why are people so hateful?

I like to read the entertainment "news", It's my brain junk food. When I'm taking a break, relaxing or otherwise have time to myself, it's just what I do.. It seems that ANY celebrity I happen to be reading about has so much hatred shot at them in the "comments" section. Why do you think that is? As a whole, we tend to put them on a pedestal, and treat them like royalty. When they're individualized, It's astonishing the things people will say about how they're living their life no matter who it is. Sandra Bullock isn't even safe! Why do people judge celebs so harshly for an outfit,lunch date, hairstyle, shopping trip, or what their kids are wearing. It's all so judgmental and we don't see behind closed doors. Any theories why people are so mean when they comment?