The best of us must sometimes eat our words.
It was, he thought, the difference between being dragged into the arena to face a battle to the death and walking into the arena with your head held high. Some people, perhaps, would say that there was little to choose between the two ways, but Dumbledore knew - and so do I, thought Harry, with a rush of fierce pride, and so did my parents - that there was all the difference in the world.
Dumbledore will only leave from Hogwarts when there are none loyal to him!