Why are there so many haters on Youtube?

I put up videos of myself singing and I get alot of love from people, but every blue moon there is alwyas someone who leaves a negative comment. And it's not like they're just saying 'i don't like your singing' they say 'you suck I u can't sing It right don't sing it at all',things like that. I don't understand y they can't just hit dislike and move on. Yes I reply back because I have a bit of a temper and then it turns into something crazy. I'm rambling now but I just want to kno y people have to b so nasty with their comments and whenu go to these people's channels i see that they left bad comments on other folks videos too. When will the hating end?