Probably 50/50, but without the influx of buyers at the bottom pushing prices up, none of it would have happened.
Many people were only willing to "pay those prices" because they never intended to actually pay them. The whole scam was get in for as little money as possible, pay as little as you can monthly, and wait 18 months for the value to go up significantly and then sell it to the next sucker who comes along. What other end-game could there be when you're barely paying the interest?
AKA house flippers...