What Is a Sunk Cost?

What Is a Sunk Cost?

Let me explain what a sunk cost is: it's money, time, or effort you've already spent and can't get back. If you let these sunk costs sway your future choices, even when it's not smart, you're setting yourself up for trouble.

Take this scenario: you've shelled out for a pricey, non-refundable eight-week online course from a top university. By week two, you see it's not enjoyable and won't help your goals. Do you keep going just because you've paid? That means more time and effort down the drain.

How Sunk Costs Work

Sunk costs show up in your personal life and in business. Once you've spent the resources—time, money, effort—they're gone for good, regardless of what happens next. In rational terms, you shouldn't let them influence your upcoming decisions.

Consider Company ABC: they've poured millions into a new product. Midway, market research reveals trends have shifted, and the product won't sell. Should they keep going or stop? A smart manager ignores the sunk costs and looks at the future— the product won't succeed. But often, companies push on to justify what's already spent, leading to bigger losses.

The Sunk Cost Fallacy

The sunk cost fallacy is when you keep going with a decision just because of what you've already put in, even if logic says stop. It's a faulty way of thinking, rooted in our dislike of waste and the urge to defend our choices.

This happens a lot in business and government. Governments pour more into over-budget infrastructure projects, justifying it with the billions already spent. Look at the U.K. and France with the Concorde: they kept funding it despite no profits. High costs, low demand, and clear signs of failure didn't stop them from investing more.

Behavioral Economics: Why the Sunk Cost Fallacy Exists

The sunk cost fallacy comes from psychology and behavioral economics. Let me break down the key concepts.

Loss aversion means you feel losses more intensely than gains, so walking away from sunk costs feels like a bigger hit—even though the loss is already done. You might cling to hope that things will improve.

Commitment bias keeps you stuck to your original plan because changing feels like admitting defeat or dealing with cognitive dissonance, where you justify bad choices to avoid discomfort.

The endowment effect makes you overvalue what you've invested in, so the perceived loss of quitting seems worse than it really is.

Avoiding Sunk Costs

You can avoid the sunk cost fallacy with awareness and deliberate steps. Here's how to do it.

Focus on future returns: Decide based on what you'll get going forward, not what you've lost. Ask yourself if you'd start this now without the past spending.

Set limits and goals upfront: Before investing, define stop points. For stocks, set a sell price if it drops. In business, review milestones and reevaluate if they're not met.

Seek external counsel: When you're emotionally invested, get advice from someone neutral. Their clear view can guide better choices.

The Bottom Line

Sunk costs are those unrecoverable expenses of time, money, or effort that too often mess with your decisions, hurting you or your business. The fallacy tricks you into thinking persistence is wise, but you need to spot the bias and choose smarter. By setting limits, getting outside input, and eyeing future returns, you can steer clear of throwing good resources after bad.