The point has been made that IF your home is invaded, and unless you are trained and comfortable with having guns, you are VERY unlikely to have a weapon right at hand, and that it is more likely the criminal will end up adding YOUR gun to his collection...

Also, if you DO have a gun, and IF you shoot at an intruder, you'd better be sure they fall inside! otherwise, they...or their relatives..may sue you, claiming 'no proof of criminal intent' or something similar.