To clarify a bit. By law, a human life is the "good" of highest value above everything else. Just committing a crime does not exempt you from that principle. Wether self defense was justified is judged by whether the level of force used was an appropriate reaction to the threat at hand. So not sure whether using a military weapon (assuming not going full automatic) vs. private actually matters at all, or if that would just be a separate violation.

It's a separate violation because you'd be breaking then also the military laws and regulations (see other comments why)

The problem with this is that you are trusting that the robber is only going to rob. Unfortunately, all too many shoot their victims anyway because the take wasn't as much as they expected or other reasons.

Calm, reasonable robber--of course you hand it over. Crazy methhead, if he makes a mistake and gives you an opportunity you very well might be better off taking it. America doesn't try to judge the situation in advance.

I don't disagree when looking at it in isolation. But my comment was specifically to Switzerland which has according to the department of statistics around 30 cases of robbery per year which basically never lead to physical harm. It is just not something you worry about in your day to day live.

Drug addicts usually want to be left alone and won't bother you. Exception being people chuck full of cocaine and alcohol in and arounds nightclubs frustrated about not getting layed.

The problem is being tackled the other way around by trying to keep poverty, inequality and thus acts of desperation low.