I disagree with the premise that making evaluations of alternatives in a relative way is irrational. Here’s a simple example to make the point. Suppose you have in your posession 10 units of food. The experimenter makes you a choice:

a) Yet one more unit of food for you, free and clear, or
b) on the flip of a coin, if heads, you get 20 more, but if tails you lose the 10 you had.

Choose a) and you then have 11 units of food.
Choose b) and you then have either 0 or 30.

The b) choice may look better to a Wall Street tycoon, provided he cares not one whit if he starves.