This is a worldwide movement, without a centralized leadership or an operating creed. So I think #2 is going to come closest to what sparked the protests to happen. I don't think it's a sense of entitlement, rather, the declining income and shrinking size of the middle class, along with the economic bite of the recession and housing crash, which have hurt average Americans more than the wealthy. They are also frustrated that those in the financial industry gambled so heavily with their money, lost, were bailed out with tax money, financed with public debt that affects poor and rich alike (money that has since been shaved out of state budgets) and finally with the startling and growing income disparity in the US.
But these things motivate a lot of people in the US who are not in the OWS protests--to vote, to run for office, to support and donate to candidates who represent the reforms they want, etc.
I think suggesting OWS is an anarchist movement is ridiculous. I also don't think it's accurate to say that so far the movement has been all that constructive. But the messages of economic pain and the need for regulation are not illegitimate ones.
I also find it interesting that conservatives are so quick to label OWS as some radical socialist anarchist self-entitled hippie crazies while those who protested in the Tea Party, weapons in hand, were simply God-fearing patriotic constitutionalists. Seems wonderfully convenient.