Hollywood and the music industry?
I really do believe that it's impossible to be an American gun owner and not see yourself as a movie character under specific circumstances
subconsciously. In other words, you can be the most self-controlled American gun owner but under a particularly stressful situation your brain may just do a quick leap to: "What did that character do again? He/She was in the same exact situation I'm in right now."
Living in America you understand that people just aren't relaxed, and a lot of it has to do with them trying to align their interactions/experiences with movies/series. Or worse, a media that sensationalizes damn near everything.
Disclaimer : I'm not American nor do I live in the US, so y'all can disregard the following and kim if you want
- Entertainment def plays a huge role. There's definitely a huge "gun-culture" being portrayed via media/entertainment (movies, hh...I mean there's a rapper called "Gunplay"

) so imo guns in the US are just so "part of the picture" that it's normal/cool to have one.
- History. We all know about the Constitution, but let's not forget that the US was built on conquering ( = stealing) land, killing native americans, enslaving Black people, the Civil War, etc. War/violence is part of the "American Dream" it seems. Wasn't there a statistic about how the US has been in some war almost all of its existence?
- The military-industrial complex. You can't promote the army/war while not making people WANT to have guns and use them. It's a huge business. Plus contrary to old European nations you guys have never been attacked on your soil so you don't really feel the need to tone down the war rhetoric.
- Culture. Capital punishment is still aroudn in the US, and y'all don't care one bit about torturing "suspects" and going through all kinds of moral loopholes to "justify" it.. Even cops killing kids cause a week-long outrage, and that's it. There is a "shyt happens"/"by all means necessary" mentality that puts gun ownership/violence above certain lives, because guns supposedly represent a "right" for some. And that "right" is worth more than some human lives. But that's not really surprising considering the history.
- Culture. It's those same loopholes that make pro-gun people say "Well a knife too can kill". Yes, but how many mass-killings are done by knives? HOw many people get killed by knives, as opposed to injured by them?
- I think a lot of Americans deep down really believe they are some sort of "chosen people". American exceptionalism if you wish. As we know, over history that has lead people to morally put themselves, and their "rights", above others. On this very site a poster once agreed with the following : "So you consider that you right to have a gun is worth more than someone's life".