Sunk Cost Fallacy

Already having spent time, money, or effort can keep someone going down a path long after it stops making sense. Quitting feels wrong even when stopping would clearly be the better move.

This bias lets prior irrecoverable investments unduly influence an ongoing choice, leading to suboptimal commitment. It shows up as continued resource allocation despite marginal returns that no longer justify further expenditure.

A person buys a nonrefundable concert ticket for $80 but feels sick on the day of the show. Instead of staying home to rest, they drag themselves out because they "already paid." The $80 is gone either way — the sunk cost is just pushing them toward the option that leaves them feeling worse.

A pharmaceutical firm has invested $400 million in a late-stage drug candidate. Phase III trials return marginal efficacy and a rising adverse-event signal, and a forward-looking net present value model — discounting projected revenue against the remaining R&D, regulatory, and launch costs — comes out negative. The portfolio committee approves continued development anyway, because the prior expenditure dominates the deliberation. That escalation persists until regulatory rejection finally forces termination, by which point another $120 million has been committed — capital that later analysis attributes directly to sunk cost anchoring rather than any genuine clinical signal.

Because money or effort has already gone in, stopping feels like it would waste that investment. That feeling is exactly what makes new facts showing continuation is worse get ignored.

Prior expenditures get encoded as a salient factor in the ongoing evaluation, creating an asymmetric pull toward continuity. That weighting constrains the revaluation process and biases the choice toward preserving what's already been committed.

Asking whether future gains actually beat future costs, without factoring in past losses at all, is the direct fix. Basing the choice only on what happens next keeps the sunk cost from distorting it.

Forward-looking cost-benefit analysis that explicitly excludes sunk expenditures from the calculation corrects the bias directly. Decision checkpoints and precommitment rules override the anchoring pull of prior investment.

Overcommitment to failing projects; Delay in reallocating resources; Escalation of losses

Adversarial actors can deliberately front-load investments — financial, emotional, or reputational — into a target party to create irrecoverable commitment anchors, then extract ongoing concessions by leveraging the target's reluctance to "waste" what has already been spent. In negotiation or procurement contexts, a counterparty can manufacture escalating sunk costs through staged contracting to lock in continued engagement even as terms deteriorate. Political or organizational manipulators can publicly associate a leader's identity with a failing initiative, making withdrawal politically costly and forcing continued resource allocation to an objectively losing course of action.

Institutionalize forward-only cost–benefit decision checkpoints that explicitly strip prior expenditures from option valuations, using structured templates that require decision-makers to list only prospective costs and returns. Pre-commit to kill criteria before projects begin — defined thresholds at which continuation is automatically halted regardless of prior investment — so the anchor of past spending cannot override evaluation at review points. Train decision teams to externalize sunk cost identification as a standing agenda item during project reviews, transforming an implicit cognitive bias into an explicit, discussable variable.