Some presumably rational people are betting on the growth of any particular company. Most rational investors go with mutual or index funds, which bet on the growth of the majority of a certain list of companies, or type of company. In the history of the stock market, this bet has never failed over any given 20-year period, even the one starting in 1928.

Of course, the stock market's never before been faced with such a huge influx of stock-owning retirees, or plausible peaks in energy and some metals--without which growth as we know it can't exist--so you pay your money and you take your chances.