"some people just have a deep conviction that a certain group of people has to be wrong"
On the other hand, some people just plain were wrong. I suspect their eagerness to see Bush trapped by failure ran away with their common sense.
Interestingly, many of these people are now revising their point of view to claim that they knew all along it would be a "cakewalk." But then, historical revision has always been second nature to the Left.