The sunk cost trap: why we can't let go

What the sunk cost trap really means

Rational decision-making evaluates options based on future costs and benefits. Past expenditures are "sunk" — they cannot be recovered regardless of future choices. Yet humans consistently factor sunk costs into decisions, escalating commitment to failing courses of action. This isn't simply irrational stubbornness. It has deep psychological roots: loss aversion makes abandoning an investment feel like crystallizing a loss. Self-justification bias makes us want to prove our earlier decisions were correct. And in organizations, accountability structures punish "wasted" spending, creating incentives to continue rather than admit failure. The result is a systematic bias toward continuation over termination, even when the evidence clearly favors stopping. Projects that should be killed at month three survive to month twelve because nobody wants to write off the first three months.

The sunk cost trap in action

Kodak's relationship with film technology is a masterclass in sunk cost reasoning. Kodak invented the digital camera in 1975 but suppressed the technology to protect its film business — a business it had invested billions in building. Every year that passed, the accumulated investment in film infrastructure made the pivot to digital feel more costly. The question was never "what is the best path forward?" but "how do we justify what we've already built?" By the time Kodak finally committed to digital, the window had closed. The sunk costs they were protecting had become worthless anyway.

What research tells us

Arkes and Blumer's 1985 studies established that sunk cost effects are pervasive across contexts. Staw's research on escalation of commitment showed that individuals who were personally responsible for an initial investment were significantly more likely to increase their commitment when the project showed signs of failure. In organizational settings, Sleesman et al.'s 2012 meta-analysis found that project, psychological, social, and structural factors all independently contribute to escalation. Self-justification, social norms around consistency, and organizational reward systems that punish "waste" combine to make sunk cost reasoning almost inevitable without deliberate structural countermeasures.

Recognizing the signs

• Justifications for continuing a project reference what has already been spent rather than expected future returns
• Project reviews compare current status to initial investment rather than to alternative uses of remaining resources
• The phrase "we've come too far to stop now" appears in discussions
• Proposals to pivot or abandon are characterized as "giving up" or "wasting" prior investment
• Nobody can clearly articulate the expected future value of continuing, only the cost of stopping
• Decision-makers who championed the initial investment are the same ones evaluating whether to continue

How to counteract the sunk cost trap

Pre-commitment to evaluation criteria is the most powerful tool. Before a project begins, define specific criteria that would trigger termination — and commit to evaluating against those criteria at regular intervals. Separate the decision-maker from the initial champion: have someone without ego invested in the original decision evaluate whether to continue. Use "kill criteria" — explicit thresholds that automatically trigger a project review. Frame continuation decisions as new investments: "Would we start this project today, knowing what we know now, if we hadn't already invested?" Anonymous input helps team members express concerns about project viability without appearing disloyal to the original decision.

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