[edit: this was in response to Pilchard -- the subsequent replies were posted while I was writing this]
I tend to agree, sort of. I've been randomly attacked by groups and by armed individuals several times in my adult life (once in Aus, three times in the US). Couldn't walk for a month one time; got some nice facial scars another; pissed my pants another time after a ******** in a truck stopped in front of me while I was cycling and fired a rifle directly at me. (Interestingly, all those attacks were in ultra-conservative religious places...)
Each time I wished in retrospect that I'd had a gun, or superhuman martial arts skills or something. But I'm not convinced the outcome would have been more favorable, even though I'm well trained with firearms and am a good shot, coming from a military family who take that stuff very seriously. My sense is that, unless you're a trained soldier or a cop, the odds of something going even more wrong are pretty high if a gun appears.
Having said that, I doubt I'd hesitate if my family were being threatened and I happened to have a suitable weapon.