"In all honesty," said Professor Quirrell, looking up at the stars, "I still don't understand it. They should have known that their lives depended on that man's success. And yet it was as if they tried to do everything they could to make his life unpleasant. To throw every possible obstacle into his way. I was not naive, Miss Granger, I did not expect the power-holders to align themselves with me so quickly - not without something in it for themselves. But their power, too, was threatened; and so I was shocked how they seemed content to step back, and leave to that man all burdens of responsibility. They sneered at his performance, remarking among themselves how they would do better in his place, though they did not condescend to step forward." Professor Quirrell shook his head as though in bemusement. "And it was the strangest thing - the Dark Wizard, that man's dread nemesis - why, those who served him leapt eagerly to their tasks. The Dark Wizard grew crueler toward his followers, and they followed him all the more. Men fought for the chance to serve him, even as those whose lives depended on that other man made free to render his life difficult... I could not understand it, Miss Granger." Professor Quirrell's face was in shadow, as he looked upward. "Perhaps, by taking on himself the curse of action, that man removed it from all others? Was that why they felt free to hinder his battle against the Dark Wizard who would have enslaved them all? Believing men would act in their own interest was not cynicism, it turned out, but sheerest optimism; in reality men do not meet so high a standard. And so in time that one realized he might do better fighting the Dark Wizard alone, than with such followers at his back."

I don't know how long he thought it would take, but it sounds like he had no idea how hard it would suck.