You are talking yourself into believing that how you feel is all about protecting her. Get real with yourself. She may be relating to men in a way that is self-destructive, but she has the right to make her own decisions and her own mistakes. It doesn't matter what you are okay with. She is not yours. You have to let go.

She is attracted to "players." That's too bad. You probably would treat her better. But she will do what she will do.