The idea that Americans do not glorify mass murderers is just laughable. That movie is sort of about that. I can give the real-life examples of the things that movie is based on, if you like.
I don't mean to suggest that this is necessarily a uniquely American issue. I don't have enough knowledge about other countries to say that for sure. But I know enough about the US to know that it is, without any doubt, an issue here. A brief story might be instructive. Back in '99 there was this thing called Columbine, it was a school shooting where iirc 14 people were killed and a bunch more wounded. It is widely considered a 'turning point' in contemporary US history with regard to school shootings and mass shootings generally, with many subsequent school and mass shooters making reference to emulating or surpassing Dylan Kleboldt and Eric Harris, the shooters. What is so interesting about the case is that it
worked. They left a record of meticulous planning which made it clear that their main goal was simply notoriety. And I know their names, and I would be surprised if you, a citizen of a country thousands of kilometers away, hadn't heard of Columbine. They are notorious. And this has basically developed further with more forms of media, such that going out by shooting a bunch of people is guaranteed to get your name in big letters all over the place.
American culture has a weird kind of fascination with violence. You can see it in the media, the existence of the saying "if it leads, it bleeds". I would say that I think it has been caused by turning war into a media spectacle which began in the Gulf War, but I think it dates back a lot further than that. It may be a weird cosmic reverberation from slavery and the genocide of indigenous people here...
