You are asking whether someone should not have picked the military career if it was the best fit for them, just because you are personally morally against what they do?

That's why i dont confound the military with the political aparatus's directing of said power. Because the military isn't murdering people for no reason - they are following (in the case of the west) a elected official's policy (which you are very welcome to dislike and oppose, as i do as well).