A year ago I might have agreed with you...but every human has their breaking point...I fear GW may have met his.
Perhaps. But I see him as being the prototypic "when the going gets tough, the tough get going" type. More definitively he takes anxiety and anger to blend into a fierce resolve to succeed. It is usually experienced as an emotional high and men at least find it almost addictive. That is why they do crazy dangerous things just for fun.
Good combat pilots and other dangerous occupations are filled with such individuals. They never break but they can be carried out feet first. That is what they will have to do with POTUS. You can shake his demeanor and confidence but not his resolve and joy in the challenge.