My ex-boss, was a sniper in Vietnam. One phrase he hated over all others was "kill them all and let God sort them out". He always labeled those who used that as pussies. He had no respect for them.
We got all sorts of good stories out of him about his time over there, but never anything involving killing other people. That was discussed only with people who were there and even then rarely. He could tell us how he could take parts off a moving car from a long distance but never would mention the obvious connection.
I am quite sure a lot of them are sociopaths or just bastards. But did we give them any other choice, the nice guys don't even finish last, they just die first.