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what is the opposite of a sunk cost? a sunk gain?
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it is called "opportunity cost."   opportunity cost is the value you lose because of a decision you made.   this is the book definition from investopedia. the difference in return between a chosen investment and one that is necessarily passed up. say you invest in a stock and it returns a paltry 2% over the year. in placing your money in the stock, you gave up the opportunity of another investment - say, a risk-free government bond yielding 6%. in this situation, your opportunity costs are 4% (6% - 2%).
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