When World War 1 ended in 1918, the US moved from a wartime economy to a peacetime economy. Growth was driven by recovery from war-torn devastation that spurred deferred spending, a boom in infrastructure rebuilding and a rapid growth of demand in consumer goods. The decade that followed WW1 came to be known as the Roaring 20s. Innovations that included the mass production of cars, the launch of cinemas that provided a new form of entertainment and developments in medicine to treat diseases that were once considered fatal. Good times were had by all, including stock-market investors. Between 1919 and 1929, US shares increased 20% a year, which equated to a six-fold jump in returns in a decade. There are some striking similarities between what happened during the Roaring 20s of the twentieth century and events that are unfolding before our eyes 100 years later. Instead of the mass production of cars powered by internal combustion engines,...