I´m dubious of PTSD cause I´m one of the scarediest cats I know, but went through all heck in Vietnam and have never had any issues with it at all.
I´d say though that psychologists and quasi-hypnotic therapy really helped my wife out of agoraphobia following the birth of our daughter some 36 years ago when it wasn´t generally understood. And the only drugs involved were over-the-counter. I´d think there could be some benefit in this to the more severe PTSD patients.
I am glad that you don’t have issues. But I assure you this has nothing to do with courage or the lack there of.
I think persons who have other undetected neurological problems are far more prone to PTSD. The problems seem to start when the the persons brain gets overloaded with events and believe it or not they don't all have too be bad events. Good events that still cause stress like a wanted promotion with more responsibilities can add too it.
When PTSD hit me I had done been through all the bad events. My job was turning around too decent pay and a position I had worked 5 years too get. But my brain was overtaxed from compensating for neurological issues and the traumatic events weren't being resolved while at the same time stress increased.
It's not just vets who can get it. You can go to the hospital for an operation and the stress of the operation and possibly some minimal damage from being put under is also known to trigger what they call Panic Attacks which can lead to Agoraphobia. For most persons it is short lived. For some the underlying neurological issues must be found and treated and that is where a lot of the falling through the cracks is happening in PTSD patients. PTSD and Anxiety Attacks very often co-exist with another or even one or several neurological things going wrong in the body. Those things can also feed the PTSD.