> But being a mental wreck along the lines that PTSD is often portrayed very clearly would negatively impact your reproductive success.
There are plenty of people with PTSD who have families (particularly, kids). Our reproductive age begins really, really, really early and our reproductive drive is incredibly strong. I don't know why mental illness like PTSD would in any way impact our ability to procreate as a species or at an individual level. It might make life more difficult and life might be filled with more suffering, but we're able to procreate under all kinds of bizarrely sub-optimal conditions.