I don't care if it's not 'normal', NOBODY. CARES.
It might be an unusual way to think, and it's perfectly fine to disagree, but how exactly are they hurting themselves? And why should someone like you care about it?
I get you might want to convince someone away from something you think is bad for them, but if they don't want to it's not your place to force them or make them feel bad about it, truth is just because something is abnormal doesn't make it bad, all she's doing is having fun.
A simple mindset won't cause a person anything bad as long as they don't act on it in drastic ways, and from what I know about this user they don't seem to be the type who would do that.
So kindly take this somewhere else, it's not your business if you don't have anything nice to say.