Yes, what led to the 2008 crisis was a misvaluation of investments. Fortunately, there exist solutions to that problem, built into the system. Short-term interbank loans, the FDIC, and nationalization. Notice how not a single American bank stole it's depositor's money... And that the rules of fractional reserves were changed, to reduce the likely hood of such a catastrophe.

There is a world of difference between that and a Ponzi scheme. How many investors took a haircut from Madoff's little game, again?