Could people with post traumatic stress disorders heal by themselves, alone, in an instant?

Maybe: It could be a misdiagnosis if it is just that easy to snap out of it but psychiatry has the possibility of rapid changes if insight is increased. You are essentially speaking of an epiphany which should not be discounted in mental health. I would offer that working with a therapist would likely catalyze this sort of improvement. Stay safe!

A miracle might : Occur. However, what you are describing is not likely to happen.