With this particular short, the PTSD is a direct result of the indoctrination process for folks like the MC. The Imperium uses all kinds of nasty shit to produce what are essentially zealotous soldiers. For pilots, the machine is the only physical form they have that can express itself in any capacity, which is alluded to in the prequel I posted later.

I took the prompt a little literally in that sense. The true horror of what they are is something very few of them actually come to terms with and offset that horror by what their between fifty and two-hundred ton war machines can do.