[generj]

Per point 2, Greenspan is kind of the worst person to make that call. There's a very good argument that he explicitly allowed that deregulation and coupled it with a series of bailouts, resulting in the "Greenspan Put". This moral hazard was then combined with very cheap credit, all at his insistence. I'd take anything Greenspan has to say about the economy with a few metric tonnes of salt - as would many people who served on the Fed Board with him. The documentary 'Money for Nothing' is a great laymen's view on this.

Similarly, the SEC isn't a super credible economic source for several reasons. One being if you are smart enough to work at Goldmans you don't work at the SEC. It's pretty self-serving for the agency in charge of regulation to argue that de-regulation was harmful. Do you know the specific economists making this argument? I'm very skeptical until I see names, and then my skepticism decreases while reading the actual paper.

I would argue that deregulation was not the central issue - which was a rise in activities which circumvented regulation, like off-balance bank trading. Greenspan shielded these new fields from regulation, and the resulting over-leverage killed banks. In addition, overly cheap credit made these activities and mortgage in general overly attractive.

There is a lot of evidence for this view, mostly in the multitude of institutions and industries which all had problems simultaneously. You can view this as a coincidence or you can view it as industries responding to incentives set by Greenspan.

TLDR Greenspan caused the housing bubble.