Its because of the way society has become sad to say. And most males don't have a positive male role model in their lives, and then don't know how to be good men, and then some idolize too much the street culture.
Most males have that whole aggression thing, which is very normal. Those men have always been, the best soldiers, the best warriors, the best fighters, the best athletes. But most in society today will say that's a bad thing, and most boys are raised being told its bad, which is wrong, its not bad, its just bad when its not properly directed, which again a positive male role model can do. A discipline, and spirituality, are huge parts of directing the aggression in the right way, which ultimately leads to the boy becoming a good, strong man.
Does being a good strong man, mean you need to be all buffed up, macho, and being able to smash people's head in? Nope, because not all men have that kind of aggression. And I've seen guys who are all buffed up, macho, and able to break heads. But just didn't know how to be good men, and they are weak. There are plenty of men out there who don't have that aggression, (not everyone is made to be a fighter/warrior/soldier) but were raised right, again having that positive influence. Its just that the men with that aggression, or warrior spirit, or mentality as its called among the people I'm mostly around, it has to be honed right, if not then you have problems, and man have I seen it, and every guy I've encountered with such problems, are always lacking, the things I've mentioned, and not all of em are bad guys. Except the ones who continue to do the very same things that got them in a world of trouble, they don't choose to learn from the mistakes, continue to hurt people, and don't even try to better themselves, in any kind of way. The bible calls men like that "good for nothing men".