this is the most radical american approach and there are many problems with it. It gives you false sense of security. Once you draw a gun better be sure you're prepared to kill otherwise you will be shot for sure.
When you kill somebody even the worse scum on earth you will be at mercy of more and more stupid law and even more stupid judges, so be prepared to go to jail either. There are many cases in history when innocent, good citizen served years in prison for defending himself or his family.
Another thing is it's hard or impossible to carry a gun everywhere you go these days.
p.s.
if you still want a gun, buy this - it will get you coveed: