I've always thought anonymous imageboards were excellent training grounds for how to deal with all of this. When there's no upvoting or ability to filter people by name, you have to learn how to deal with people who often truly are only posting to make you mad. There are two good responses, both of which are extremely difficult if you have no practice: ignoring it; engaging sincerely and with the assumption that the other person is doing the same. If you persist with the first they'll eventually go and bother someone else, but this is doubly hard because it requires everyone to ignore them, and that only really happens when the bait has grown stale. The second often results in them switching from the troll persona to actual sincerity, but it requires several back and forths of responding with goodwill to bile, and I think it's even harder to accomplish in forums where people have tied their name to their opinions.