Sunk cost fallacy

The sunk cost fallacy is the tendency to continue an endeavor once an investment in money, effort, or time has been made, even when the rational choice is to abandon it. The fallacy is driven by loss aversion: the unrecovered investment is perceived as a loss, and the prospect of admitting that loss — by terminating the project — is more painful than the prospect of throwing good resources after bad in the hope of eventual recovery.

The fallacy operates at every scale, from the individual who finishes a bad book because they have already read half of it, to the nation that continues a war because the lives already lost would 'be wasted' if the war ended. At the institutional level, it is one of the primary mechanisms of escalation of commitment, in which projects are sustained not by projected returns but by the psychological cost of acknowledging failure. The rational response to sunk costs is to ignore them, but the emotional response is to escalate — and in organizations, the emotional response is often institutionalized as policy.