Exactly right Brain.
Take Rick for instance.
He starts off getting shot in the first episode, which has to be very traumatic in its own right.
You get a snapshot of Rick's mindset right before he get's shot the second time, which puts him in the hospital. After the first bullet hits his vest, he gets up and says, "Can you believe that? he shot me."
If the first shot didn't shock him mentally, the second one definitely did.
And since that point he hasn't had any chance to "catch his breath" so to speak.
He wakes up in a world that would absolutely stun any of us, and then he finds out his family is missing.
Then he deals with extreme forms of violence both against he undead and the living.
He finds his family and then finds out his wife and best friend have been carrying on. And then he finds out his wife is preggers, with him maybe not being the father.
His best friend then attempts to kill him.
Oh and in between all that he witnesses his son being shot and almost dies. And he feels guilty for losing one of the members of this group– a small child who can't defend herself.
My gosh, who wouldn't be transformed after going through all that?