It is their mindset and it is so rigid and deep that they cannot see what the rest of the world can see
It's not as clear cut as you make it out though. I am sure there are a lot of people from a lot of different countries that envy the right to bear arms.
We have seen recently many
civilians in Ukraine take up arms and fight against a tyrannical invasion of their homeland, to do this they needed guns. Would Putin have gone to war if he knew behind every door was an AK47?
The Nazi gun laws in 1938 specifically prohibited Jews from owning firearms in contrast to relatively relaxed laws to the 'law abiding german' and we know what happened there.
This is not to definitively say, Putin wouldn't have invaded, or the holocaust wouldn't have happened, we can't know this answer, but I don't think it is a stretch to say it made it easier.
Even Karl Marx argued that the working class should not be disarmed.
I believe the checks and regulations need to be much tighter in the US (similar to how Canada does it) and it is crazy to me you can't buy a pint at 18 but can buy a gun, I just think there is much more to it than just 'ban the guns' its a very complicated issue.