Bowling for Columbine

I just saw Bowling for Columbine (2002), a documentary movie motivated by the massacre of columbine, where 2 students killed a lot of colleagues in their school. It´s an interesting quest for the reason of so much violence in USAmerican society. And for every hypothesis, the movie shows examples of other countries that disqualify it. So the question remains, at least explicitly, unanswered: why are USAmericans violent?  Posted at 22:32