An unfortunate number of Americans have faced foreclosure. Neither the banks, nor the homeowners want this to occur. Banks don't want it to occur because they are forced to write down foreclosures, which in turn runs the risk of the bank failing. Meanwhile, homeowners obviously don't want to lose their homes.
Most foreclosures originate from bad lending practice at the start of the lending process. It used to be that home buyers had to show 30% of the list value of the home as a down payment, and one year's worth of pay stubs to receive a mortgage. Equal opportunity in lending laws meant that this was deemed discriminatory. When this was combined with an incentive structure that paid huge commissions for loan origination, based on the value of the loan, the end result was ultimately predictable.
The loans that were written are poorly conceived, and the ultimate consequences can be seen in the financial section of your local newspaper, and in the Wall Street Journal, where they have made the front page. Most of the bank failures we have observed so far have come from banks leveraging mortgage driven securities.