While that was ridiculous, I am not going to judge the entire city of Chicago based on the actions of some teenagers. Teenagers are morons. I know. I have two of them now.
And this kind of crap happens everywhere. In the progressive, upper middle-class town of Connecticut where I live, there are two public high schools. The kids who go to both schools grew up together playing sports in town leagues or in music classes or other activities. Yet, for reasons I'll never understand, these two schools can't have a basketball game or football game against each other without a major fight breaking out after (and one year in the game itself). If we ever do build a colony on Mars, I would be in favor of sending all children up there from the ages of 13 to 18.