If everyone had guns, thugs, thieves, druggies, mentally ill people, and any other bad people would think twice about shooting at someone or going on a rampage.
We certainly wouldn’t have 40 dead in a nightclub, or 20 dead at a high school. It would be maybe 1 dead before shooter put down.
Guns for everyone. If you’re an American citizen you have the right to own a firearm regardless of what type of person you are. Anything less is infringement upon the Second Amendment. Registries, background checks, “Felon in possession of firearm”, all that bullshit is infringement and it is unconstitutional.
If someone wants a gun they get it anyways. So level the playing field.
No one is stronger on the 2nd amendment than I am; my wife and I collect vintage firearms. But in my experience your theory doesn't actually hold up. The psychos that I have had to deal with over the years do not generally think about the consequences of their actions. A naked psycho with a hand gun once pulled the trigger several times while it was pointed at me at close range. It was by the grace of God that he had loaded his magazine wrong and that I am still around to talk about it. He intended to commit suicide and hoped to take someone with him.