Endowment Effect
Divestiture Aversion · Mere Ownership Effect
The tendency to value something more highly simply because you own it. Sellers consistently price their possessions above what buyers are willing to pay.
Origin
Economist Richard Thaler coined the term "endowment effect" in 1980 to describe the pattern where people demand much more to give up an object they own than they would pay to acquire it. Drawing on Kahneman and Tversky's 1979 prospect theory, Thaler explained the effect as a manifestation of "loss aversion"—the generalization that losses are psychologically weighted substantially more than objectively commensurate gains. Empirical studies consistently show that people's willingness to pay (WTP) to acquire an object is lower than the least amount they'll accept (WTA) to surrender that same object, even when obtained minutes earlier.