Many people, who are interested in sales forecasting, are familiar with the book Predictably Irrational by Dan Ariely. The abstract of the book states: “Dan Ariely refutes the common assumption that we behave in fundamentally rational ways. From drinking coffee to losing weight, from buying a car to choosing a romantic partner, we consistently overpay, underestimate, and procrastinate. Yet these misguided behaviors are neither random nor senseless. They're systematic and predictable—making us predictably irrational.”
The irrationality of human decisions is the basis of behavioral economics. Predictably Irrational, and many other books, give many examples which argue the idea of consumer rationality. Businesses are irrational too, as they are guided by human beings.