In the wake of the Eldred decision, Lessig has posted a heart-rending self-examination, a classic crisis of faith.
It hurts to lose. There is a such a belief of justice in the world, of good triumphing over evil. Principled people who want to make the world a better place and believe in doing good works, tend to be particularly vulnerable to this process.
It's an intrinsic problem. If you believe one person (you) can make a difference, it can be crushing to be defeated (contrariwise, if believed you couldn't make a difference, you wouldn't have tried in the first place).
As the saying goes: "Remember, no matter how hard you work, no matter how right you are - sometimes the dragon wins."