Well as Harry told them " SUCKS TO BE YOU " ! It's only to be expected really. The Wizengamot elects a weak minister so they can buy their way out of anything. When Harry won they new he was too powerful for them to control so threw him away. Now they need him to destroy the next Dark Lord and he's simply told them to do it yourself. And if they stopped being sheeple they wouldn't likely have a hard time of it. After all, they do out number the dark forces.