From The Stray Thought Bin - 'Committment'

Anthropologist Margaret Mead is said to have said,

“Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has.”

Well, I don't know if that's the only thing.
I would certainly add that a small group of committed people with an inadequate grasp of what's going on, can thoughtfully and royally foul things up beyond all recognition.