In talking to gun owners, I find they hold some pretty strange beliefs. For example, the belief that they need to protect themselves against the government, which is itching to disarm them. I've said "do you really think you're going to win if they send the Army after you? With tanks, and drones?". The scenario is paranoid, and totally unrealistic. I think it has to do with some feeling of powerlessness, and guns make them feel more powerful.
Toxic masculinity is also at play, and that is often intertwined with domestic violence (often perpetrated by cops themselves), with guns being the phallic symbol of masculine power. In this case, it's like a dominance display. The fetishization of guns is tied up with this power/masculinity nexus, imo.
I've also spoken to hobbyists, and the bottom line for them is also really power and pleasure. They enjoy firing their guns because it gives them a sense of competence and power in an uncertain world. They seem oblivious to the obvious social problems that readily available assault weapon availability causes in America. I see it as profound lack of empathy and refusal to see an obvious cause and effect between easy availability and mass shootings.