Serious question; after what happened in Season 1, there’s no way he’d not have serious PTSD. Debbie too for that matter!
This could have been a pretty engaging character point; instead it seems kind of weird how Mark is just “fine” while Debbie is breaking down alone and no one, not even Cecil, has recommended they get a therapist.
Therapy is mental health medical treatment, analogous to physical medical treatment; albeit with entirely unique challenges, it is just as important to maintain ones mental health with as much care as ones physical health. After being beaten to pieces by his own father, Mark was treated for his physical wounds, but not his mental ones. Why not?
As for your analogy, it covers a very specific minority of people, who went through a vastly different experience. PTSD is not the same for everyone, it varies massively depending on the specific circumstances of what happened and how it impacted the victim.
I think you’re coming at this in bad faith and with a very narrow view point.