Incredulity reflects how people really believe that other people may, in fact, operate in some sort of rational world. When we think of ourselves, for the most part, we tend to think we would make rational decisions in all circumstances we were faced in, especially those we are NOT in.

Irrationality of consumers is great for the retail economy, though, and while it defies years of economic logic, behavioral economics has been in the spotlight for many things these days, more so than simple rational-consumer theory.

(perhaps it's simply the logic of smart poor people in a stupid/deranged society?)