In all the situations you mention, an armed citizen could have drastically reduced, or moderately increased, the carnage. Depends on the citizen. CCW folks have, in the recent past, performed admirably in a couple of mad-gunman emergencies, but past performance is no guarantee of similar future success.
So you go ahead and use your own gun to protect your own self, or your own family. More firepower to you. But don’t try to start sheepdogging me. I’m not your little lamb. In an emergency, I don’t think I’d be inclined to want much help from a lone, armed, self-appointed, civilian volunteer. Joyeux noel.
Good enough. You are truly an island among men. I feel confident that in an emergency you’ll require no assistance from anybody. Good Luck and God bless.