Sunk Cost Fallacy
Throwing good money after bad - sticking with a losing path because of what you already spent. Sunk costs are gone; ignore them.
- Term
- Sunk cost fallacy
- Is
- Continuing because of unrecoverable past spend
- Right test
- Future costs vs future benefits only
- Cure
- Ignore what's already gone
Forms & parts of speech
Definition in plain terms
The sunk cost fallacy is the mistake of continuing to invest in something - a project, a channel, a strategy - because of the money, time, or effort already spent on it, rather than because it's the best choice going forward.
A sunk cost is a cost that has already been incurred and cannot be recovered no matter what you do next. Rational decision-making says that only future costs and benefits should matter, because the past spending is gone either way.
But people feel a strong psychological pull to "not waste" what they've already put in, which leads them to keep pouring resources into failing efforts to justify the original investment.
The fallacy is treating unrecoverable past costs as a reason to continue, when they're irrelevant to whether continuing is wise.
Why it matters to growth leaders
The sunk cost fallacy is a constant trap in growth, where teams invest heavily in campaigns, channels, products, and strategies that don't pan out. The pull to keep going - because of the budget already spent, the months of work, the public commitment - is powerful and expensive.
A growth leader who recognizes the fallacy can make the harder, better call: evaluating whether to continue based only on expected future return, treating everything already spent as gone and irrelevant.
This is the discipline behind killing a failing campaign without regret, abandoning a feature that isn't working, or reallocating away from a channel that has stopped delivering, regardless of how much was poured in.
It pairs with opportunity cost: the resources freed by abandoning a sunk-cost trap can go to something with real future value. Resisting the sunk cost fallacy is what separates disciplined resource allocation from emotional escalation.
The growth leader recognizes this as the sunk cost fallacy: the money and effort already spent are gone and unrecoverable no matter what happens next, so they're irrelevant to whether continuing is wise.
The only rational test is forward-looking - whether the expected future return from more investment beats the alternatives. Evaluated that way, the channel doesn't justify another dollar; its future prospects are weak.
The leader makes the disciplined call to stop, treating the past spend as the sunk cost it is rather than a reason to escalate. Pairing the decision with opportunity cost, the freed budget and attention go to a channel with real future value.
By resisting the powerful pull to throw good money after bad, the growth leader practices disciplined resource allocation - deciding on future value, not on the emotional weight of what's already gone.
Synonyms & antonyms
Synonyms
Antonyms
Origin & history
The sunk cost fallacy describes the irrational pull to continue an effort because of unrecoverable past investment; rational decision-making weighs only future costs and benefits, making sunk costs irrelevant to whether to proceed.
Etymology: source.
Usage trends
Search interest for this term over the last five years:
Common questions
- What is the sunk cost fallacy?
- The tendency to keep investing in a failing initiative because of resources already committed — money, time, or effort that can't be recovered — instead of deciding purely on future costs and benefits.
- Why are sunk costs irrelevant to decisions?
- Because they're already spent and unrecoverable no matter what you do next, so only future costs and benefits should determine whether continuing is the best choice.
- How does a growth leader avoid the sunk cost fallacy?
- By evaluating whether to continue based only on expected future return, treating everything already spent as gone — which enables killing failing campaigns and reallocating to higher future value.
Related tools & calculators
Resources & people to follow
- referenceWikipedia — sunk cost
- referenceBehavioral-economics and growth practice
- referenceRGM analysis — sunk costs are gone; decide on future value, not on the emotional weight of what's already spent
Curated, non-competitor resources verified per term.
Related training
Disciplines
Areas of marketing where sunk cost fallacy is a core concern: