A film does not have to appeal to everyone to make money. Red Dawn I was pretty stupid, but it apparently make a lot as a rental, so they made a remake. I don't have any idea how many Diehard films they have been. Those I have seen were essentially extreme violence and special FX punctuated by funny quips. No one gat any Oscars, but they did make a lot of money.
If you tell people what the cannot have, it can become a fad, and they want it. I have noticed that old VW's especially the convertibles, are worth a fortune. The original cars were underpowered, noisy, and did not handle very well, but there was some cuteness about them that Datsun 210's lacked. Guns are far less useful than VW's: you cannot drive one to work, and they are for many people more of a fad. Plus it is easier to collect guns than cars because they are smaller.
Violent crime is lower in the US because the population is older, and many fewer people have served in the military. Ex military people as a rule feel more affection for guns than those who have not been in the military. I do not think that the crime rate is lower because there are more guns.