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Endowment effect 0:53
A 53-second explainer of Endowment effect, narrated over the same demo you can try yourself.
Try the interactive Endowment effect demo
What this video covers
The endowment effect is the way owning something - even briefly, even just feeling like you own it - makes you value it more than you would if you didn't. The price you'd accept to give a thing up is reliably higher than the price you'd have paid to get it, simply because now it's yours.
Notice the gap: the price you'd sell your mug for is higher than the price you'd pay for the very same mug. Nothing about the mug changed - only whether it was "yours". That's the endowment effect, and it's why letting people feel ownership early (a trial, a saved basket, a personalised set-up) makes giving it up feel like a loss rather than a neutral choice.