I wondered when you would get around to me.
The world is full of atomic bombs.
https://www.armscontrol.org/factsheets/Nuclearweaponswhohaswhat
I will always believe that the focus should be on identifying the criminal in order to prevent these types of crimes and that our best defense against them is learning how to protect ourselves as best we can in any situation. In my mind, it is no different than learning how to protect ourselves against the impact of fires, floods, hurricanes, etc...
If for some reason guns are ever banned the people intent on committing murder and mayhem will hijack a plane, blow up a truck filled with fertilizer, drive a truck through a crowded public place, etc...
We all have a responsibility to learn and teach the people we love to use our wits and be survivors in life.