I am very young.
I have seen some very VERY traumatizing things for my age short of military combat.
I agree that as a young man the images of both warfare and death don't have much of an effect, even the real thing seems almost detached from me. The death of another, or myself, has little effect. My mind stays focused on the situation and the situation alone, where it belongs.
Emotions of tragedy have this awful effect on me, by hitting me months later instead of immediately. I think its a natural reaction, but while I empathize with everyone in any situation, to actually take on those emotions is very difficult to impossible for me.
I think that the more time one has to think about these things, the worse it gets, as one gets older, the amount of heartbreak and tragedy one sees increases exponentially.
The older one gets, families, wives, children, are added to the mix. As a young man, I am not that much different from the soldiers in WW2 or indeed many of the veterans on this board when they first joined up. Idealistic, cocky, bulletproof with nothing or no one to loose. Horrors... I have plenty of time to forget about them... Pain... Young man, life is ahead of me, pain now is inconsequential... Death.... nothing I can do about it, and Its not gonna happen for a long time to me.
I think once you get old, you have more to think about and more to loose, and even at age 18, there are a few tragedies in my life where I sit alone in a dark seclusive mood and think "What if I had...."
If your 50, and have had gone through life's tough situations....
I can only shudder to think how many "What ifs" you have time to ask.
