Can someone with an unlimited amount of money compromize the network?
With unlimited money, you could destroy almost anything. I don't really see why it matters. If someone with unlimited money spends a few billion dollars to destroy Bitcoin, we'll just create Bitcoin2 and maybe he'll spend another few billion destroying that. We can keep creating new crypto-currencies indefinitely. If each one gets a few billion dollars out of the hands of some evil entity, that's a win in my book.