I think it's pretty clear that some fraction of people enjoy upsetting other people, though it would surprise me if most of them wildly underestimate how much damage they do.

Why would this surprise you? As I understand it, most of the damage is caused by the pattern, not by any single instance, and the inferential distance in such a case is extremely high. (I find it fairly high personally, as a man who is trying to be sympathetic and has read discussion about this more than once. I'm having trouble estimating how high it would be among the sort of person who would actually engage in the behavior.)