It wasn't either of them. It sounds good for party politics, but it's too simplistic. You get 2008 after a decade of foolish monitary and fiscal policy. The bubble popped when it became obvious that you can't base a healthy economy where everyone gets a McMansion with a workforce full of mortgage brokers and wedding planners.
good point, but the bubble was popped at the most optimal time by those who wanted Baracka Obama