The fact that guns make it easier to kill people is well covered above.

What there has been less said about is that the Wild West mentality seems so oddly prevalent in the US psyche - and that there seems to be an endless stream of US - oriented or originated propaganda from Hollywood and from rap music and from metal music and etc etc to the broad effect that violence and guns are the only manly answers and ways to solve problems. These things have made Clint Eastwood, Sylvester Stallone, Steven Seagal and Jean-Claude van Damme stars.