Why are people so mean ?

I think i’m starting to see why most people have stopped coming to Yahoo Answers for advice or to ask for their views etc on things because some people on here come off as very rude and judgmental. I think I might stop coming on this site myself, people are horrible and then they wonder why some of us have trust issues. This isn’t the first time i’ve dealt with rude people on Y/A or on social media in general either. This is why I am afraid to open up to people because they are mean,  I am a decent person and I don’t deserve to be treated in that way. Why can’t people be more understanding of other peoples issues instead of judging them all the time? I’m starting to think we have a lot of narcissists on here.