Booms and bull runs lead to “irrational exuberance”, a term coined by Alan Greenspan, former chairman of the US Federal Reserve, in 1996. More than a century before him, author Charles Mackay explained the phenomenon succinctly in his aptly titled book, Extraordinary Popular Delusions and the Madness of Crowds. He presciently wrote, “Every age has its peculiar folly...into which it plunges, spurred on by the love of gain, the necessity of excitement, or the mere force of imitation.”