How so? Also, what aspersions does that cast on all those regulars who have got PTSD over the years?
How so? One can reasonably expect those who are more resilient and actively seek to put themselves in harm's way to be less prone to PTSD than those put in the same position from a random sample. It doesn't make those individuals immune from PTSD.
It doesn't cast any aspersions, it's simply an inconvenient fact for those who think as you do.