The most productive people in the world have never cared about finance or banking.
The only similarity between anything YC related and the credit crisis is that some business models are purely designed to catch a bubble. If you do that you are just speculating with code rather than financial instruments.
True entrepreneurship adds value and builds businesses that you can self-fund and that people will pay for, without trying to lure in a million visitors and a few investors with some sort of undisclosed, roulette-wheel business model.