Until knife killings start to rise (UK). Beyond this, I've seen several interventions of armed citizens stopping a crime in progress, when the police are still in route. When seconds count, the police are only minutes away.

My dad was ex-army, retired PD (detective, undercover) and a heavy 2A advocate. I grew up with guns around so it wasn't some weird, scary thing to see. I have many friends who also are heavy 2A who also grew up with guns in the home. It's first a matter of familiarity and second a matter of civil defense. I'm not a fan of "must flea" laws, and not a fan of restricting gun rights at all.

And yeah, if you can afford a tank and the ammo for it, as far as I'm concerned, you should be able to own and operate it. I would draw the line at nuclear weapons and materials.