I believe our generation has a disease. Narcissism. I'm sure it is worse in the states than anywhere else but the youth of America and the world in general, thanks to the media, has become a generation of self centered, inconsiderate morons. When our parents and grandparents were growing up the world was a different place. There were wars, depressions, recessions and everything was in shambles. During those times I think people realized that the only true value in life is life itself and they took advantage of that and looked out for one another as well. Nowadays people have way too much money, are way too fat and don't care about anything that doesn't effect the little technological bubble they live in. Really I blame the abuse of technology and the media (which is a result of technology) for creating this generation of narcissists. You no longer even need to leave your home to interact with your "friends" because it can all be done online. Instead of talking to people on public transit people just plug in their headphones and tune everyone out. After removing yourself from humanity this much people actually start believing in the delusion they are living that they are the only important person in the world and that no one else matters. Then if that isn't bad enough the media comes along and reinforces this mindset by telling people they need to look the best, dress the best, act a certain way, buy more of this or that as if they are the center of the universe and they should only be concerned with their appearance and their material possessions. The world is run on greed and greed alone. The only reason the media tries to influence people is not because they actually care how you look, act or dress but because you have money to spend and they want it so whatever method of brainwashing they can figure out they will try it and the saddest part is most people fall for it and continue the cycle. Like I said, the world was a different place when our parents and grandparents grew up. Very few people were "rich" and most were just working to get by. With the current downfall of the world economy I can only hope for another full blown depression to open up peoples eyes. Maybe for once people will place some kind of value on real relationships with people they know and people they will only maybe meet once in their life; place some kind of value on life as a whole, not just their own; place some kind of value on experiences, life, love and laughter instead of placing all value on their possessions and themselves.
I believe there is still hope for this world. It is just disgusting that it ever got to this point and that it is going to take so much to reverse it.
Hopefully you are able to make the connection here to your story. The connection being that the reason those guys acted like that towards that girl is because modern society is training them not to care about anyone but themselves so they saw nothing wrong with tormenting an innocent needy person.
That is all.