If you sat down with your grandfather or grandmother and had to explain both the narrow focus of the movie "The Big Short", and more broadly, explained the financial collapse of 2008/2009, what would you tell me?

{responses should be at least a couple paragraphs and cover the major devices used/misused in the financialcollapse: mortgage backed securities, credit default swaps, collateralizeddebt obligations, rating agencies. subprime mortgages, etc, etc)