Most people are not able to withstand being criticized and publicly laughed at for over four years running. The press treated George W. Bush horribly in his second term. I think Mr. Bush just became worn down and dispirited by the ongoing battle. The pressure to keep a stiff upper republican lip was heavy, especially with his father still being alive then. I guess I have some amount of mercy for him.
It did not help that he wasn’t as bold as Trump, in that he, Bush felt he could not bite back at the idiots and call them out. Most politicians are nowhere near as tough, as resilient as Donald Trump was. Most human beings in general could not cope with that sustained level of animosity, day in day out. It still amazes me, what Trump was able to tolerate, yet continue pushing his policies, many sucesssfully.
George W Bush was told by Obama to either cooperate or to expect a one way ticket to the Hague for war crimes.