Time plays a factor that may not be well controlled for here. As you get older the actions you have taken and the events you have participated in can impact you in new ways.
The risk perhaps not so much moral injury, but that combat and war is almost like a drug. Imagine going back home to a toddler raging about the wrong color cup, a narrow set of civil rules, and flipping burgers after living a life out the back of a pickup truck with nothing but a rifle and your buddies keeping you alive. Fucking boring. But I'm no killer, just a guy who spent a few months in a civil war, and met a lo…
Watch that and tell me if you think it's still cool and normal life is boring. I find that it snaps me right back out of "Hollywood war" thinking and makes my stomach turn.