Allowing banks to make loans to unqualified people is the root of the housing bubble mess.

Allowing credit institutions to create credit based upon a trivial amount of capital in order to allow individuals to buy pre-existing assets is at the root of all bubbles.

The requirement by the shareholders of credit institutions for continual growth of profits means in turn that when the market of "credit worthy" people is saturated, they have to extend it in one way or another to "unqualified" people, as you say.

"The future is already here -- it's just not very evenly distributed" William Gibson