The real estate bubble and the financial crisis in 2008 that followed was due to oversight failure, pure and simple. Rather than address that failure, the government bailed out everyone.
The regulators were relying on the same assumption (of uncorrelated real estate markets state-by-state) by the credit ratings agencies.
The investors, ratings agencies, and regulators all believed in the same incorrect assumption. If that assumption had been correct, the crisis would never have happened.
The investors, ratings agencies, and regulators all believed in the same incorrect assumption. If that assumption had been correct, the crisis would never have happened.