Here's a fresh take, and one I personally find quite credible.

This crisis is less about demonically predatory lenders, and more of an analysis about how a lot of very typical cognitive errors lead everyone (buyers, lenders, regulators) into dangerous ground...

http://meganmcardle.theatlantic.com/archives/2008/10/how_did_it_all_happen.php
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The charm of fishing is that it is the pursuit of what is elusive but attainable, a perpetual series of occasions for hope. -John Buchan