If a group of armed intruders are attempting to kick in the front door into your home, It would be abnormal psychology in that moment to have their well-being near the top of your priority list, when your own self and any other occupants of your home should be your primary concern. Sure, taking a human life might be a little traumatic, but nowhere near as traumatic if it were me or one of my loved ones who were harmed or killed instead. Also, I would rather live with a little trauma than not live it all (due to being murdered in my own living room).
It's a small sample size, but I know a few people who survived violent conflicts by killing the perp.
100% of them feel pretty good about their choice.
We so often hear that non-violent self defense will do the job....they have it all planned out:
Their kung fu is that good. Or they'll kick the perp in the nuts (always a man, eh?).
But not once have I heard anyone say they did this successfully.
The real world scoffs at our plans for violent conflict to be predictable.
So tis better to plan for the worst, since it's easier to do something less extreme, than
prepare for the best & encounter the worst.