bias library
Endowment effect
You value what you already own more than what you would pay to acquire it.
Kahneman, Knetsch, and Thaler (1990) measured this with coffee mugs. Owners demanded roughly twice what non-owners would pay for the same mug. In crypto, the bias attaches to the bag you've held since 2021, the coin you "discovered early", the protocol you've been "long term on" since launch.
What it looks like in crypto
- ●You hold a coin because you were "early" — your identity as a trader is partly tied to having discovered it.
- ●A position has been in your portfolio for three years, through a bear market, and your reasons to hold are now mostly historical rather than forward-looking.
- ●You can describe why you would never sell, but you cannot describe why you would buy it again today at the current price.
- ●The coin has sentimental value because of when you bought it, who told you about it, or what it represented at the time. None of these are reasons the market will care about.
- Once a month, ask of every position: "If I had only cash today, would I buy this asset at the current price?" If no, consider selling. The bag is not part of you.
- Force the question with a hard rule: every six months, every position must justify its weight from scratch. Defaults expire.
- Separate the asset from the story you tell about it. The asset is on a chart. The story is a memory.
- If a position has been held longer than your average holding period, the burden of proof shifts: you need active reasons to keep it, not passive inertia.
Worth knowing
The endowment effect is gentler than loss aversion — it lets you keep a bag without acute pain — but it is more persistent. The damage is what could have been earned with that capital deployed elsewhere. Every portfolio has dead weight. Naming it is the first action.
Kahneman, Knetsch & Thaler (1990). Experimental Tests of the Endowment Effect and the Coase Theorem. JPE, 98(6), 1325–1348.
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