This article by Michael Lewis explains the roots of the financial crisis in great detail, but is understandable enough that people without finance backgrounds can understand it.
“I’d never taken an accounting course, never run a business, never even had savings of my own to manage. I stumbled into a job at Salomon Brothers in 1985 and stumbled out much richer three years later, and even though I wrote a book about the experience, the whole thing still strikes me as preposterous—which is one of the reasons the money was so easy to walk away from. I figured the situation was unsustainable. Sooner rather than later, someone was going to identify me, along with a lot of people more or less like me, as a fraud. Sooner rather than later, there would come a Great Reckoning when Wall Street would wake up and hundreds if not thousands of young people like me, who had no business making huge bets with other people’s money, would be expelled from finance.”