That's generally the rationale for allowing "self-defense" weapons.
Do you remember...or have you heard of...the LA Riots? The ones in 1992?
I was the manager of a shoe store at the time. I did a really stupid thing. I've done a bunch of stupid things, but I think this one was top of the list. When the riots happened, the owners/managers of the little strip mall in which my store sat locked everything up and they left. Or rather, they tried to. Some of them weren't able to do so.
I didn't try. I got on the roof with my father's shotgun (which hadn't been fired in twenty years...) and just sat there, watching the rioters...none of whom had guns, btw...as they broke into all the stores in the area and looted and destroyed to their heart's content. Except, they didn't loot my store or the ones next to it. This forty something year old fat woman holding a shotgun on the roof made them say...er...not this one. I didn't shoot anybody. I didn't say anything. I just sat on the roof. Holding the gun.
But because of that experience, I really can't blithely dismiss the 'self-defense' thing, y'know? Especially since a friend of mine, who managed a 'dollar store' five stores down from me, was beaten up when she obeyed her bosses and did not resist the rioters when they came to her store. She ended up with a broken arm, nose and ribs.
The second amendment wasn't written to ensure that individuals can have guns to protect themselves against burglars, not really. It was written so ensure that we, the people, would never be entirely at the mercy of a dictatorial government. It was written to ensure that the people remained 'the government.' It was written so that someone could sit on the roof of her store and keep rioters from destroying everything.
I am not against decent and strict regulations regarding the acquisition and possession of guns. I think they should be at least as regulated as driver's licenses are. The problem is that the 'opposition' wouldn't be happy with that. They want a complete ban.
And that, given human history and what happens when a government utterly disarms it's populace, is a really lousy idea. What would be a good idea is that all those who have/own guns be rigorously screened and trained--and licensed. With requirements to renew licenses, with classes.