It also makes it much easier to hold a building hostage. Light a fire or explode a bomb, and then have your gang surround the exits and mow everyone down. That’s how the massacres went down at the Columbine school shooting, or at the Egyptian Mosque with 220 dead to 40 gunmen the other day. There’s no way you can dual wield pistols like you’re playing Halo and shoot your way out when guys are already positioned around the building with their guns trained at the exits, and there’s a raging fire spreading at your back. Especially when the bad guys are probably well prepared with a stockpile of homemade explosives, a high caliber AR with a bump stock, are mentally composed after a dose of valerian, and are wearing heavy body armor like a modern Ned Kelly. You on the other hand were caught off-guard at a concert with your girlfriend and with nothing to protect you except for a T-shirt and a shitty revolver. If you think the odds could ever go in your favor then you’re confusing your world with a make-believe cowboy fiction where the good guys always win.
Banning guns in Japan did reduce the amount of violent crimes dramatically, and deaths to violent crimes, and the same has been proven globally. You’re about as likely to be mugged in London as in New York, but you’re about 4 times less likely to die in London from one because you’ll probably just get smacked with a blunt object, cut or stabbed rather than taking multiple gunshot wounds.
Now if you still want to try for the argument that as civilians can viably fight back against government tanks, cruise missiles and drones with civilian weapons, then use that argument. But don’t bother to pretend that it’s desirable for every person to carry a pistol, at all times or we’d somehow be safer from terrorists. Accidents, misfires, friendly fire, and death due to rapid escalations would greatly surpass any lives saved even if we all took the time to train to be accurate shooters.
Suppose again that everyone at the concert in Vegas had pulled out their guns at once. Well, you can bet there would be trigger-happy friendly fire from people who thought, “Oh shit, that creepy guy in the crowd just pulled out his gun too, he must be one of the shooter’s buddies! I’ll just point my gun at him to be safe-oh, he’s turning his gun at me now-I’ve got to shoot him!” Or something similar would happen when nerves were frayed even after the guy was dead, like if a dark skinned guy happened to suddenly walk around a corner carrying a gun.
Also, if I were to be forced into a once-in-a-lifetime fight to the death, I think I would better enjoy a longer fight. Westworld’s gunfights end before they get good, and don’t fairly reward the guys who worked out at the gym or who studied martial arts for years like a hero just in case they ever needed it. And longer fights are better because someone is more likely to come along and deescalate the situation or help out.