I’d like the world to be one where anybody intent on shooting up a Wally World will change their mind based on the sure knowledge that they’ll get plugged in the back by a pink Kel-Tec wielded by Mrs. McGillicuddy, but this world is not yet that world, and likely never will be.
Most people don’t get carry permits, and even those who do mostly don’t carry their guns. The odds of a mass shooting are already like a lightning bolt or meteor strike. The odds of a mass shooting happening within 25 yards of a truly skilled shooter with a USPSA GM ticket or FAST coin are “meteor strike in your back yard that goes through the hoop of the basketball goal in your driveway and gets nothing but net” rare.
The sensible thing to do, it would seem, would be to train civilians to the “truly skilled” level. I don’t see this happening either.