I'm convinced that the reason video games and movies aimed at young males in America are devoted almost solely to fantasies about super-heroes and supernatural power (especially the power to kill) is because adolescent boys feel so impotent, so powerless, so unlike real men. The adults in this culture do not furnish any meaningful alternative scripts. That's the market's job, I guess.
When confused and disturbed young men do act, they sometimes act out the scripts of violent retribution that the video game and movie business so lavishly supply to them. This is a culture, lately, with no room whatsoever for tenderness. Look for a moment of tenderness in the popular video game, Carmageddon. The Speaker of the House's moments of tender reminiscence are reserved for himself. This used to be known as a condition called feeling sorry for yourself. It was considered, if anything, un-manly.
I don't know if the ambient political mood of the USA is any more poisonous now than it was for about a decade starting in the 1960s, when all those assassinations changed history: John Kennedy, Martin Luther King, Bobby Kennedy, George Wallace, plus Lennon and the attempts on Ford and Reagan. The Baby Boomers produced more than their share of lost souls. Myth still shrouds the doings of Lee Harvey Oswald, since he was bumped off so quickly, but other shooters have been around for decades.