Actually those statistics you're talking about usual involve them being raped by other men.
I think the major difference is our respective definitions of predator and monster. I believe that to term a human a monster, you must believe them incorrigible, inhuman and unrepentant. Serial-crimes are perpetuated by monsters.
When I think 'predator', I think 'wolf', and wolves are awesome- just not a good thing for modern society. In a similar sense, human predators with the 'alpha male' mindset and pack mentality had their place, but they don't anymore. In that way there's still some useful places for those old-world souls, but they're few and niche.
If we were ever thrown in a Lord of the Flies type situation, I would be thankful for (albeit wary of) those same predators. I would not want to be stuck with a monster.
I think it important that you realize society is not a "Lord of the Flies type situation". There's no real reason for a transgendered person to be discriminated against. Being different REALLY isn't enough. If you dislike the concept of transgenderism then that's okay, you're entitled to that, but you still shouldn't discriminate against that person for believing otherwise. I'm not entirely sure what you're getting at any more, but i'll say this: If a man, or boy, discriminates or rapes a transgendered individual, it's because that person is either a monster, or wasn't raised properly. In my experience, very few people are actually monsters. Which means that society is simply not teaching them the "proper values". I'm not even talking about society at large either. Modern popular culture and values in the US extoll tolerance as one of the most important things in life, with acceptance and understanding not far behind. If men are truly predators as you've described, then to a transgendered person who suffers from discrimination then they are horrible monsters indeed. The sad thing is, it's place like your boarding school that instill these fucked up morals.
It's "old world" values that teach children to be your so called predators. Like I said though, they're really not predators. Real predators are hunters, and hunters don't judge the quality of a kill by the clothes it's wearing, or the thoughts in its head. No, those children are monsters. Would a hungry wolf care what gender you were? I don't think so.
But you see, monsters, well all they do is discriminate, and that's what the people you describe do. They cause pain, agony, and discriminate. They become this because they are taught this. Generally by such institutions that seek to standardize and quantize everything.