Who says the insane don’t do things on purpose?
Usually people call someone insane as a way to say whatever they are doing isn’t their fault, no sane person would do what they are doing.
He’s doing it on purpose, it is his fault, he’s not insane. He’s a very, very angry and evil person.
Angry and evil people do things that regular people would never consider doing. If some people think they’re insane, they don’t care, in the ned they’ve been duped by them as well.