Speaking for my own abuser, he is the only subject in his entire world. The rest of the universe is full of objects only. He has demonstrated (to clinicians, not just to me) that he has no ability whatsoever to realize that other people are capable of feeling different things than he does, so if something makes him feel good, it makes even the little child he's doing it to feel good too.
He has said on a number of occasions that he (still, in his late 60s) struggles to believe things continue to exist when he can't see them. Even if you're sitting across a table from him and can clearly see behind him, he doesn't believe the things behind him continue to exist, even though you can see them.
I suspect he's on a pretty extreme end of a spectrum there, but that some version of that underlies a lot of trauma. Adults are doing something to meet some need or desire they have, without enough awareness that the (usually young) person in front of them is experiencing it totally differently.