There never is only one factor, but I find it that if you ever root the problem back to the begining, it is often Congress passing a law that allowed it in the first place, or "regulating" it without taking into account all off the consequences for their actions. Like Dodd and AIG Bonuses. He allowed them to get the bonuses, then tried to make it seem like it was all them being greedy.
Imagine that in a Grander scale. Instead of allowing Freedom and Liberty, they pass laws and people adapt their lifestyles. What was the last law Congress passed that grew your Freedoms? I can't think of one.