Even if it was someone with bad intentions, how are you making the situation any better by shooting at that person? That person has a family, a history, you don't know why he's there. Wouldn't be better way to be to scare them off without a gun, not risking injuring him, yourself or any one else in your household (what if you have kids and they come out of their rooms to see what's going on and you shoot them?) and just letting the police deal with it and getting him a proper punishment.

I don't get that 'I'd better get my gun', guns are very dangerous, and split second decisions made using guns are never the right ones. If you want to grab a weapon, grab a sword or a knife. You can defend yourself or your family with it, but you are not exactly likely to kill/harm someone accidentally. You are much more likely to pull the trigger than to stab someones eye out.

If you rely on guns to keep you safe, you are delusional. A gun is a danger to anyone in the house, and if you shoot someone, you have to live with that. No person is pure evil, everyone has reasons why they do evil things. If you are willing to kill someone you don't know just because he's in your house, it makes you a killer.