That's the same argument I got from Mael a few years back when this shit was going on in my actual backyard. (spoiler: I survived without a gun)
Telling everyone they need a gun to protect themselves from the other psychos with guns is a pretty laughable argument, honestly. Every human in the world should be in their own personal arms race against the boogeyman? It's like the NRA specifically came up with that argument to keep themselves in business.
I'm not even in favour of more gun control at this point, i strongly doubt it would work, but most of the justifications people come up with against gun control are just as silly as believing you can ban guns.
Legislate parenting. Require abortions when a child is not going to be raised by 2 sensible adults, jail the parents if they stop parenting the kids between 0-15 years. Shut down the internet, or bust it back to dialup speeds. Probably solves a healthy amount of the homegrown terrorist shootings in the US, IMO.
(Yes, I realize that is WAY sillier than gun control, whatev)