Self defense against what? I have never felt the need to have one or felt threatened in the slighest. Even though i was going in one of shit spot in brussels for years wearing a suit and a briefcase.
Guns only escaladate the situation, pulling one out, when you are threatened by one, most of the time result in one of the party ending up dead instead of no one harmed.
In america out of the 15 000+ homicide comited per year 12 000+ are done with guns, if you remove those you would have nearly the same numbers as the one in europe per capita.
That's a telling exemple.
And those most likely applying to have one are insecure ass who shouldn't be let near one in the first place.