There's a lot of FB employees on HN and I wager a lot of them know how scummy their employer is. Yes, many are staying for the paycheck (and because leaving a job isn't an easy thing for everyone), but I know several who are staying because they feel that their position is where they can produce the most good for the world.
Similarly, I know many people in politics who despise who/what they work for, but keep at it because that is where they can make a difference.
It doesn't always work. But it also doesn't make me think less of them. At least of the ones who aren't staying because of the $.