@elston_ Note that 1/100 (or so) human being do not feel any emotional trauma when it comes to killing other humans.
These humans are highly sought after as agents of the government, as members of special military operation groups etc.
It is interesting to ponder, that in nature, it is rare for animals of the same race to kill each other. It happens, but it is rare.
Therefore, it is somewhat biologically hard coded into us no to kill other human beings.