I'm a military physician, and I was a line officer before that. I have watched people die and brought one back to life. I have trained to kill and save. I have brought a ship alongside suspect vessels for boarding and sent men into flooded engineering spaces. In my mind, the most important of those is that I have sent my people into harm's way. I would argue, from a leadership perspective, the hallowed-vs-not argument is a red herring. The money is trivia. The indirect utility of deterrence is not measurable and therefore frankly doesn't matter.

But the toll on your own people has real consequences that you can prevent. Killing someone is the sort of thing that makes you question your own right to life. Don't do that to people unless you have to, and by "have to", I mean there is an imminent threat to life. You don't "have to" pay taxes. Someone's going to come after you, but they're not going to kill you over it. You don't have to kill prisoners.