You will be paid oodles of money if and only if your next decision is irrational. What should you do?
(There are standard cases in the literature where you lose a lot unless you become irrational, say by taking an irrationality potion. The case at hand differs significantly from those, because it concerns the next decision. You can't just rationally decide to take an irrationality potion, because doing so would constitute your next decision and that would be rational.)