Why do people hate on other people?

It's so ridiculous how people treat other people. Everything has to be so negative. If you put out a youtube video and you're an amazing singer, thousands of people hate you. If you put out a picture and you're absolutely gorgeous, thousands of people tell you you look like a transvestite. I mean, I see people being rude to other people all the time and it's uncalled for. Why are people so mean on the internet?