I wonder how much popular culture has to do with it. For example, when you sincerely listen to rap lyrics, a lot of it (and from the biggest names too) sound like a deranged, narcissistic, and sometimes violent, rants. When people hear that around them from the youngest age, they get the understandsting that such outlook on life is within the accepted norms (or, more likely, the music tells them to don't care about any norms at all, because it's all about the benjamins or whatever), especially when they don't have parents or other authority figures to correct them. Smart people from decent backgrounds can see through this filth or even use it as harmless entertainment - but, for other people, it can instill antisocial behaviour.