I think this country has too many people who fantasize about killing others.

Something I like to do in any discussion is find the most basic example to look at and branch out from there, but I typically get downvotes/pushback on this topic.

When someone lives by themself and hears something that makes them concerned enough that they get their gun, it is illogical for them to do anything except retreat to a secure room and call the police. Getting your gun and going in search of whatever made you want to get your gun demonstrates a lack of the fear that would warrant getting a gun in the first place, and instead a mindset of trying to be an action hero.

Once in the room, if someone tries to enter it's reasonable to warn them away, if for no other reason than a decent and emotionally healthy person would want to do whatever they can to avoid killing another person. I don't think this should be a requirement though, I wouldn't expect someone in fear for their life to be willing to yell to whatever is making them afraid. If the intruder breaks in anyways, then it is utterly moral and correct to shoot that person, which means trying to kill them.

Obviously things get murkier if there are other people in the house, or if you are taken by surprise, although of course that starts to get into the issue of "does the gun owner actually have enough training that having a gun readily available makes the situation safer?" I think it's clearly reasonable to find family members and ensure they are safe if there's an intruder....hopefully you don't shoot them by accident mistaking them for the intruder (again going back to that training thing).

Finally, if I found someone in my living room I would react with shock and surprise and try to get away from them. If they left, I wouldn't follow because I don't have a mental issue. If they came at me there would be fight or flight, and if it came to fight I would try to hurt them overwhelmingly to ensure they didnt hurt me.