Rapists and murderers are risk takers with a can-do attitude and a record of accomplishing what they set out to do. Those are attractive traits.
Granted, women prefer if men rape and murder people other than themselves, but rapist-murderers still demonstrate the fundamentals of being providers, wheras being a non-murderous incel only implies the opposite.
"If you can't even rape and murder a bitch, how will you take care of our kid?", the woman wonders.
No one cheers for a failed rapist or a wannabe murderer, those people are losers. Like being an virgin, unattractive in a man.