The bombers and drones kill at a distance. But the mano-a-mano killing on the group is up close and personal and well you get to see people die or get blown up. I expect the ground battlers are the ones who have the most problem with what they do. I mean if you are 6000 miles away in a safe place manipulating drones that drop explosive devices and blow up people you don't get a front-row seat to witness the results of your handiwork. You go home at night or wherever and sleep peacefully. Whereas the ground soldier gets to watch his buddies die or get blown up at close range.
I dunno. War is he**. Why would anyone anywhere engage in it without doing everything possible to avoid it? Blood lust?