Instead, Thaler began to keep a list. On the list were a lot of irrational things people do that economists claim that they don’t do, because economists presume that people are rational. At the top of the list was their willingness to pay 100 times more to avoid a one-in-a-thousand chance of being infected with an incurable disease than they were for the cure for that same disease, after they already had a one-in-a-thousand chance of having it.