You don't know that, maybe it's one monster case of post-traumatic stress disorder and he really believed in his country as he went into Vietnam. I'd like to see the records too, but I'll bet everything will be pretty normal for someone in his situation.
It's strange how much people can change. Kerry was a relative hero in Vietnam while IMO Bush took the easy rich-boy out to avoid getting hurt or interrupting his party schedule. Yet now Kerry's an unpatriotic chicken and Bush is showing some serious patriotic backbone.