I have guns. I'm not ever going to shoot one in the middle of a crowd of people. 90+% of bullets miss their target in actual combat.

If I was carrying my gun and a mass shooter went off, I also probably wouldn't engage. My little 9mm is good against a carjacker or a mugger with a knife. It's mostly for dealing with wild hogs - I shoot about 1 a week with it.

In a mass shooting, the rule is to escape. If you can't escape you hide. If you can't escape or hide, fight back. Having a gun on me doesn't change that, and I'm certainly not volunteering to get in a gunfight against a crazy person with a long gun, extra ammo, and no concern about collateral damage armed with only my little pocket pistol.

One issue with that is that you need a lot of coordination, cooperation, and community behind you. We're not just dealing with the fascist police, we're dealing with the fascist cultists here. We still have a host of people who disagree with this regime as well that are horribly squeamish on what it takes to defeat fascists.