Investors are moody. But when it comes to their views of stocks, they can be downright manic-depressive. Assets ranging from bonds to commodities to real estate have had their hot streaks, only to be abandoned later, of course. But when it comes to equities, long bull markets inspire the view that investors in stocks can't go wrong, given enough time. And dismal decades like the current one tend to be greeted with proclamations that the party for stocks is permanently over.