However, looking at the significantly large and unparalleled dimension of the current crisis, one will have to assume that there must have been other serious contributory factors.
In fact, if you recollect, the crisis originated in a small segment of the US financial system – the subprime market – and many were generally sanguine and had even dismissed the crisis initially as a small and localized one which did not have enough potential to spread to, and impact other segments.