Give someone a mug, and they'll suddenly demand twice its price to sell it back
In 1990, Daniel Kahneman, Jack Knetsch and Richard Thaler handed Cornell students coffee mugs, then let owners set a selling price and non-owners set a buying price. Owners wanted roughly double what buyers would pay, even though standard theory says merely owning an item shouldn't change its value. The gap, driven by loss aversion, also meant real bargaining frictions the Coase theorem assumes away.