Online Bullying Hurts me

I am heartbroken by what I heard from a social media girl who has been bullied recently. I don’t want to name her. I saw her story on instagram and awful comments about her. I’m just wondering how people can be so cruel to another human being who they don’t even know? Is it from pure jealousy of the girl or what is it that drives people to be so cruel? After what happened to Caroline flack, how is this allowed continue? The girl is very pretty and appears a lovely person. I found a site where people were saying nasty things about her and I posted on it a nice post about her and politely told the people to leave her alone and unless they have personally experienced her being bad to them then not to comment negatively and my comment was deleted and I was banned due to my “spam” Who runs these sites?? They are enabling bullying. Saddens me