Depends. Most people who are mugging you are going to be threatening you with a weapon in order to do so.

Otherwise, who the fuck would give them anything? The implication is, "If you don't do what I tell you, I'm going to kill you.", which is always a threat to a persons life, and you cannot rely on the generosity of a person robbing and threatening your life to not just kill you after they get what they claim to be after.

Vigilante would be you going after them after the fact. I.e. you know the guy who robbed you.. they left, the life threatening situation is over with. You then precede to go out of your way to find them, kill them, etc.

Of course all of this is just mental masturbation and the blathering of peoples self righteous indignation over perceived wrongs, etc. The reality is, if someone is threatening you in order to rob you, you would be a fucking fool to try to stop them with a firearm because either they don't have a gun at all.... or they already have one aimed at you.

And who the fuck is ready for that? You would need to be walking around at all times with chambered weapon in your hands in order to defend against this kind of thing...

That doesn't happen.