It wasn't a housing bubble, it was a credit bubble.
Gather your own information, and you will come to the same conclusion.
Dean Baker reports on NPR reporting that "one investment bank had a contract with New Century, a leading issuer of subprime mortgages, that it would reject no more than 2.5 percent of its loans".
One of the first commenters asks about The Giant Pool of Money, the This American Life hour that nails this credit bubble issue down, easily. Not even hard. Seriously, go listen, the reporting is not hard and you will know what happened.
Not housing bubble, credit bubble. Get that part clear before you think you know what happened.