Both of my grandfathers, my father, 3 uncles and 2 brothers saw combat. If fireworks bothered them they never ever told anyone about it.
I believe it is psychological. If you are told about a malady long enough you can get that malady.
My grandfather saw combat in Korea including serious combat injuries during the war. He hated china, but loved fireworks, and explosives in general, especially on Independence day. He whipped our butts, when me and a cousin threw some under his chair, but that had nothing to do with him being a veteran.
I think it’s a mixture of psychology like you said, and a general wussification of our culture and especially the American male.
“I believe it is psychological”
No, there is a simpler explanation. PTSD allows them to get a check every month for the rest of their lives. That has a way of enhancing the diagnosis count of PTSD.
Fraud in service disability determination has been a disgraceful part of military separation for a long time. This is its logical extension of that “tradition”