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You’re two hours into a film you stopped enjoying an hour ago. You stay anyway. You paid for the ticket.
Or it’s bigger than a film. It’s a degree you’re halfway through and no longer want. A business that has eaten three years. A plan you’ve told everyone about. Every part of you knows it isn’t working, and one thought keeps you there: but I’ve already put so much into it.
That thought has a name. It’s called the sunk cost fallacy, and once you can see it, you start noticing it everywhere.
What Is the Sunk Cost Fallacy?
A sunk cost is anything you’ve already spent and can’t get back: money, time, effort, years. It’s gone, whatever you decide next.
The sunk cost fallacy is the habit of letting that spent, unrecoverable cost decide what you do now. You keep going with something because of what it has already cost you, not because of what it will give you from here on.
Here’s the simple test economists use. Only two things should matter in a decision:
- What will this cost me from now on?
- What will it give me from now on?
What you’ve already spent isn’t on that list. It’s the same whether you stay or go. It can’t change, so it shouldn’t steer.
That sounds obvious written down. In real life it’s one of the hardest things a person can do.
The Theater Ticket Experiment
The most famous test of this idea happened at a university theater in Ohio. In 1985, psychologists Hal Arkes and Catherine Blumer set up a simple experiment. People lining up to buy season tickets were randomly given one of three deals: full price, a small discount, or a big discount.
Everyone got the same tickets to the same plays. The only difference was how much they had paid.
Then the researchers counted who actually showed up. Over the first half of the season, the people who paid full price went to more plays than the people who got discounts. Same shows, same seats, same evenings. The ones who had paid more simply felt more pulled to “get their money’s worth.”
In the same research, Arkes and Blumer asked people to imagine something else. You’ve accidentally booked two trips for the same weekend, and neither can be refunded. One cost more. The other, you’re told, you’d enjoy more. Many people chose the pricier trip anyway. They picked the weekend they’d like less, because it had cost them more.
Nothing about the future changed. Only the past did. And the past won.
Why Your Brain Does This
Here’s the part most articles on the sunk cost fallacy skip, and it’s the most surprising part.
In 1999, Hal Arkes teamed up with Peter Ayton to ask a strange question: do animals and young children fall for this? They reviewed the research and reported that they could find no clear-cut case of the fallacy in animals. They also found that young children, put in situations like this, often chose more sensibly than adults did.
Their explanation is worth sitting with. Adults learn a good rule early in life: don’t waste. Finish your plate. Use what you bought. Don’t throw good things away. It’s a wise rule most of the time. The trouble is that we learn it so well we stretch it too far. We apply it even when “not wasting” means throwing more time and money into something that’s already lost.
So the sunk cost fallacy isn’t a sign that you’re foolish. It’s what happens when a good habit gets used in the wrong place.
The science didn’t stop there. In 2018, a team at the University of Minnesota published a study in Science that complicated the animal picture. They gave mice, rats and people matching tasks. The animals waited for food; the people waited for short videos. All three showed the same pattern: the longer they had already waited, the less likely they were to give up.
But there was a detail in that study that matters a lot for real life. The pull only kicked in after a decision to commit had been made. While they were still deciding whether to start, they weighed the cost fairly. Once they’d committed, the time already spent began to hold them in place.
The researchers are still debating what exactly is going on in animals. But the practical lesson is clear. Your judgment is clearest at the door, before you walk in. Once you’re inside, the past starts voting.
Where the Sunk Cost Fallacy Shows Up
It hides in small things and huge ones:
- Food: eating a meal you don’t want because it cost a lot.
- Shows and books: finishing a series you stopped enjoying three episodes ago.
- Study: pushing on with a course or degree that no longer fits, because of the years already spent.
- Work: staying in a job that is slowly draining you because “I’ve built so much here.”
- Money: holding a losing investment because selling would make the loss “real.”
- Projects: teams and governments pouring more into a plan everyone privately knows has failed. The fallacy even has a second name, the Concorde fallacy, after the supersonic jet that Britain and France kept funding long after the business case had fallen apart.
If you’re stuck on a decision like this right now, it may also help to read about why some decisions freeze us completely. Sunk costs are one of the heaviest weights on the scale.
When Staying Is Not the Sunk Cost Fallacy
Here’s a line worth drawing carefully, because this idea gets misused.
Not every reason to stay is a sunk cost. Some reasons point forward, not back.
- You know something others don’t. Maybe the project looks like it’s failing, but you can see that it’s close to working. Staying for that reason isn’t a fallacy. It’s information about the future.
- Your word is part of the value. Some commitments aren’t investments at all. They’re promises. A marriage, a child, a friend in a hard season, a promise you made to someone who is counting on you. The worth of keeping that promise doesn’t live in the past. It lives in the future, in the person who is trusting you and in the kind of person you’re becoming by keeping it.
- Finishing is the point. Sometimes the value of a thing is in completing it: the skill you build by pushing through, the trust you build by following through.
So the honest question isn’t “Should I ever quit?” It’s this: Am I staying because of what’s ahead, or only because of what’s behind?
If the only answer you can find is “because of what I’ve already spent,” that’s the fallacy talking.
How to Stop Falling for the Sunk Cost Fallacy
You don’t need money, a coach or a therapist for any of these. Just a quiet minute and some honesty.
- Take the “new door” test. Imagine you’re standing at the door for the very first time, knowing everything you know now. Would you walk in? If the answer is no, the only thing keeping you inside is the past.
- Say the sunk cost out loud. “I’ve spent four years on this.” Naming it shrinks it. It’s a fact about yesterday, not an instruction for tomorrow.
- Ask what the next year will cost. Not the last year. The next one. Your time, your health, your peace, your relationships.
- Remember what you keep. Walking away from a plan doesn’t erase what you learned. The skills, the lessons and the person you grew into come with you.
- Check what really matters to you. It’s much easier to let go of a plan when you’re clear about what you’re actually living for. Our free core values finder takes a few minutes and can make the next step clearer.
The Man Who Wrote Off His Whole Résumé
There’s an old letter, nearly two thousand years old, where a man does something most of us find almost impossible.
His name was Paul. He had spent his whole youth becoming the most qualified person in his world. The right family. The best teachers. Strict training. A spotless record. More zeal than anyone around him. It was the kind of investment people build a whole identity on.
In the letter, he lists all of it, one credential after another, like a man adding up exactly what he has sunk into his life. And then he writes it off. He calls it loss. He talks about forgetting what is behind and reaching toward what is ahead.
He isn’t saying those years were worthless. He’s saying something better had come into view, and he refused to let everything he’d already spent keep him from walking toward it.
That’s the freedom underneath all of this. What’s behind you is real, and it isn’t wasted. But it doesn’t get the final vote. Some people find that easier to believe when they trust that their future is held by God, and not only by what they’ve already paid.
Walking Out of the Theater
The next time you catch yourself thinking “but I’ve already put so much into it,” pause.
Thank the past for what it taught you. Then ask the only question that can actually help: From here, what is worth my next hour, my next year?
Sometimes the answer will be to stay and keep your word. Sometimes it will be to stand up, leave the ticket on the seat and walk out into the daylight. Either way, you’ll be choosing for the road ahead of you, not the one behind.
Discussion Question
Which is harder to walk away from: something you’ve spent a lot of money on, or something you’ve spent a lot of time on? Tell us which one, and why, in the comments.
Share This
“I stayed three more years because I’d already spent two.” Turns out that’s a named thinking trap. This explains the sunk cost fallacy better than anything I’ve read: https://bgodinspired.com/index.php/personal-growth-and-life-skills/what-is-the-sunk-cost-fallacy/
Wild detail: researchers found young kids often avoid the sunk cost fallacy better than adults do. We learn “don’t waste” so well we apply it to things that are already lost. https://bgodinspired.com/index.php/personal-growth-and-life-skills/what-is-the-sunk-cost-fallacy/
The one question that got me unstuck: “If I were walking through this door for the first time today, would I go in?” https://bgodinspired.com/index.php/personal-growth-and-life-skills/what-is-the-sunk-cost-fallacy/
Questions People Ask About the Sunk Cost Fallacy
What is the sunk cost fallacy in simple words?
The sunk cost fallacy is the habit of continuing something because of the money, time or effort already spent on it, instead of judging it by what it will cost and give from now on. Because past costs cannot be recovered whether you continue or stop, they should not decide the choice. Only future costs and future benefits should.
What is an example of the sunk cost fallacy?
A classic example comes from a 1985 study by psychologists Hal Arkes and Catherine Blumer. Theater season ticket buyers were randomly given full price or discounts, and over the first half of the season the people who paid full price attended more plays, even though everyone had identical tickets. Everyday examples include finishing a meal you do not want because it was expensive, or staying in a failing project because of the years already put into it.
Why do people fall for the sunk cost fallacy?
One leading explanation, from psychologists Hal Arkes and Peter Ayton in 1999, is that adults overapply a useful rule: “don’t waste.” People learn early to finish and use what they paid for, then extend that rule to situations where continuing only wastes more. A 2018 study in Science also found that mice, rats and humans become less willing to quit the longer they have already waited, but only after they have committed to a choice.
Is it always wrong to stay because of what you’ve invested?
No. Staying is not the sunk cost fallacy when the reason points to the future, such as private knowledge that a project is close to succeeding, the value of keeping a promise to someone who depends on you, or the skill and trust built by finishing. The sunk cost fallacy only applies when the sole reason to continue is what has already been spent.
How do you avoid the sunk cost fallacy?
A simple method is the “new door” test: imagine facing the decision for the first time today, with everything you now know, and ask whether you would still choose it. Naming the sunk cost out loud, estimating what the next year will cost rather than the last one, and getting clear on your core values also make it easier to decide based on what is ahead rather than what is behind.
You might also find this helpful: How do I know if God wants me to quit my job?
