The internet can be a playground for people like that, sadly there are little to no repercussions for their actions so nothing to stop them. Really it sounds like they are unhappy/bitter people if this is what they choose to do.

I have a tough time dealing with unpleasantly behaved people myself, what I try to do is not take it personally and not react negatively, I don't want to become dragged into it myself.

Sounds like you did a good job of keeping your distance there, you kept your cool- well done.