Chances are you know someone who sells his stocks only if they have gone up, never if they have gone down.
Or the person who regularly runs up credit card debt but would never think of dipping into her savings account.
Or maybe the guy who refuses to pay $15 to have someone else mow his lawn but wouldn't dream of mowing anyone else's lawn for $15.
And what about those folks who flock to all-you-can-eat buffets and cell-phone plans with unlimited minutes?
According to traditional economic theory, such people shouldn't exist. People aren't supposed to careen through life systematically making bad bets, leaving money on the table, assigning different values to the same products and paying too much for things they don't really want. Homo economicus is supposed to make intelligent, rational choices that maximize his or her wealth and financial well-being. (Your Irrationality Is Predictable, WashPost via Sasha)