Negative comments

seem to be the only thing some people post on social media and comment forums.
I came across another one this morning. This time it was directed at me. The person who made it had not read what I had to say very carefully. He assumed I was saying one thing when I was, quite clearly, saying something else. Other people had understood me and commented favourably. He was not happy about this. 
I have "blocked" him. I can't be bothered with that sort of negative behaviour. But, it did set me thinking.
Last year I sat down and wrote a short autobiography of my childhood. A few people have read it and later this year it will be given to the person who requested I write it for an archive of such things. 
One of the people who read it is my friend R... She is a retired doctor and former politician. I like her a lot. She has a sense of humour, an inquiring mind and a realistic view of the world.
"It amazes me you turned out the way you did," she told me, "I'd understand if you hated some people."
What, I asked her, is the point of hating anyone? I don't think I actually hate anyone. I hate the things some people do but I don't think I hate anyone I actually know. As for anyone else, I'll reserve judgment until I meet them. 
I don't necessarily like everyone I know. I would prefer not to spend time with some people - and I don't spend time with them by choice even if I must spend time with them by necessity. "Hate" though seems to me to be such a negative emotion I don't want to waste energy indulging in it.
But I do try not to spend time on social media or comment forums being consistently negative. So, why do people do it? 
I have, out of curiosity, taken a look at the "profiles" of a number of such people. By that I mean I have run my eye down a fairly lengthy list of their comments - such people tend to be frequent commenters - to see what sort of comments they make to other people. Some of them seem to post "smart" comments at every opportunity. They seem to trawl through a post on a news website and make a negative comment about almost every other response there. If someone is foolish enough to disagree with them they get upset. They are prolific but don't really contribute to any discussion.
I wonder who these people are. What are they like in real life? Do they use social media in this way because they lack friends in real life? If so, I think I feel sorry for them.
Social media can be fun. For the most part I enjoy it. I haven't sought out a huge number of "followers" or "friends". I don't feel the need to do that. I like to think that I might one day meet some of the people who have been kind enough to comment here and elsewhere. I suspect I will like them. I also think that I should treat people here and elsewhere in just the same way as I would treat the people I have face to fact contact with on a daily basis. 
So, if you are reading this, "Hello."