There is a certain type of woman who likes guys who are willing to do bad things to other people, as long as it's not them. That way, they get to feel like a "princess" (i.e. respected by someone who respects almost no one else, so they're a special snowflake exception). If it's proven that they'll go to extremes, so much the better, 'cuz here's a guy who will do anything to protect her.
This is messed up, obviously, and they're a small minority. They don't want to be treated like crap, they want their boyfriend to treat other people like crap. Problem is for some of them the respect-for-girlfriend thing's just an act, and one which they'll drop sooner or later.
And there are also severely low self-esteem women who attract abusers like flies and often end up believing they deserve no better. Again, far from normal.
Also there are male narcissists who project a lot of unwarranted (but genuinely self-believed) confidence, which is superficially attractive... but then the women quickly leave once they realize that there's nothing there. They can "get a lot of girls" but usually only for a short time - which is frustrating to them, because if they're looking for more notches on their belt then most women can see it coming and dump them before sex happens, and if they're looking for a long-term lover (read: worshipper) then a quick lay won't be enough.
This whole "violent alpha male" nonsense is taking some rather uncommon situations, completely misunderstanding the dynamics, and then projecting it as something which is common and normal.