It is not that simple. For a single person, you're correct. The issue in the US is the same that underlies nearly all US problems - political corruption.

Back in the 70s, the NRA was a group that supporters hunters. Then they started gettting money from gun makers, and making specific donations to politicians to get gun laws changed. Lots more guns and ammo were sold. Gun makers saw this as a really good deal. They repeated that corruption loop over and over.

Fast forward 40+ years and you get 90% of Americans who want real background checks for buying a gun, and 0% chance that such legislation will pass.

Americans aren't stupid. They are about as smart as humans anywhere. They ARE the most propaganized people I've ever seen (I've never lived in North Korea). Propaganda & corruption go hand in hand, and viola, we have Americans dying like flies from gun violence.