Even if that were true - and it's objectively not - sinking to that level does nobody any good.

Take care of yourself, and don't worry overmuch about people on the internet being wrong, would be my take:-). (Also, they cannot ban you here - hexbear.net is an entire instance, and BestOfLemmy is not a community that resides on it, but rather Lemmy.World)

I wouldn't put it so aggressively, but I stopped arguing with one of them recently, because I realized that I was punching down. I'm not going to try and diagnose, but some sort of neurodivergence that leads to hyperfocusing on irrelevant details, and black and white thinking.

I don't think the answer is insulting them, that just validates their ingroup/outgroup mentality. The best thing to do is to just encourage them to keep on trying to improve themselves, and try to work on their maturity for when they become adults.