The lesson seems to be "take on more debt than you can afford and someone will come along to change the terms of your loan agreement so you don't have to pay what you said you would." How will that teach them a valuable lesson? They end up better off than the people who took on only as much debt as they could afford.
There is also a lesson for the lenders and builders involved in the subprime McMansion boom.
The average foreclosure costs $50-60k. It is often cheaper for a bank to allow the delinquent payer to pay the teaser rates - and lose some of the interest - than it would be for the bank to foreclose and try to re-sell the property