You've been told the answer to this many times and it remains as clear today as it ever was.
Developed countries all over the planet have mentally ill people just like the US does but far less gun violence and lower murder rates. It is common sense that the one distinguishing factor is in the US mentally ill people have easy access to the tools of mass murder and in other developed countries they don't.
Seriously, this is basic, common sense.
What they do not have is an ingrained highly devoted gun culture that values the innate right of all living things to self defense.
You,as a city dwelling liberal in a city with a massive police presence have with time and local experience and few gun traditions or opportunity for sport, have become indifferent to others for whom firearms are part of the culture.
You want others to think as you do because you define rational subjectively.
Your reason looks poefectly rational according to your conditions but I don’t think thinking rationally from personal conditions is rational.
As I have suggested gun grabbers create fear in those who value their guns and the cultural madness over the issue has destroyed rational dialogue.
You see the present day Supreme Court as a problem to overcome. I see gun grabbers as part of the reason conservatives spent decades in a successful effort to create it as it is. I want that ended too, minus the imposition of radical 2nd amendment restrictions.