The 2008 financial crisis of the US was a watershed for economics discipline, especially macroeconomics. Several world leaders such as the Queen of England questioned distinguished economists of Ivey league schools such as the London School of Economics on why they failed to see what was happening and had not prevented the crisis through policy advice? Most did not have an answer. Why? One of the reasons is the supply side economics, which is also called Monetarism; and the Chicago School of Economics, which advocates that free markets function efficiently and self-regulate; and at best governments should tinker with monetary policy of money supply; has become the dominant intellectual basis for policy making for the last forty years. Models of this kind failed to predict the financial crisis because they are based on strong assumptions. I sketch out the causes of the crisis.