The Sunk Cost Trap: How Your Brain Keeps You Stuck in Bad Decisions

A company invested millions of dollars into developing a new software product. Despite numerous signs that the project is not viable and market demand is lacking, the team decides to continue to invest more money and resources, hoping to turn things around.

An investor buys shares in a company, and the stock's value plummets due to poor performance and negative news. Instead of selling the shares and cutting losses, the investor holds onto the stock, unwilling to realize the loss and hoping it will recover, even though the company's outlook remains bleak.

Your friend is in a long-term relationship that has become increasingly unhappy and unfulfilling. They continue the relationship because they have already invested several years into it, even though they have both been miserable for some time.

The sunk cost cycle is a self-reinforcing cycle where the fear of losing past investments prompts further investment, leading to "throwing good money after bad"

The Sunk Cost Fallacy

The sunk cost fallacy is a cognitive bias that leads us to continue investing in a decision, relationship or project based on the cumulative prior investment (time, money, resources) despite new evidence suggesting that the cost, moving forward, outweighs the benefits.

This fallacy occurs because the sunk costs—costs that have already been incurred and cannot be recovered—are irrationally considered when making future decisions, even though these costs should be irrelevant.

You see this bias everywhere:

• A business keeps sinking money into an underperforming project.

• You stay late every night on a side hustle that drains your energy, but feels important because you’ve been at it so long.

• You stick with a client, course, or strategy long after the data says it’s time to pivot.

All because your brain whispers: “You’ve already invested so much—don’t stop now.”

This isn’t courage. It’s cognitive inertia.

Perhaps the most famous real-world example of the sunk cost fallacy is known as the Concorde fallacy. In the 1960s and ’70s, the British and French governments jointly invested in the Concorde—a supersonic passenger jet designed to cut transatlantic flight time in half. The technology was extraordinary. The economics were not.

Costs ballooned. Demand was limited. Environmental concerns mounted. Yet the project continued—largely because so much time, money, and political capital had already been invested. IThe total development cost of the project is estimated to have been roughly $1.3 billion to $1.44 billion by the time of its completion

The Neuroscience Lens

From a brain science perspective, the sunk cost fallacy is tied to how we process risk, reward, and loss. Your nervous system is wired to avoid loss and justify past decisions even when doing so compounds future costs. The amygdala lights up at potential loss, overshadowing the prefrontal cortex, which would otherwise help you make a rational assessment of future outcomes. This tilt toward emotion over reason is why we stay in a failing strategy or relationship long past its “sell date.”

The sunk cost fallacy isn’t an enemy—it’s a human quirk. It's not about quitting. It’s about deciding with clarity, not compulsion. Once you recognize it, you can use psychology for you, not against you.

What “Sunk Cost” Really Means

In economics, a sunk cost is a cost that’s already been incurred and cannot be recovered. Rational decision-making says you should ignore what’s already gone and decide based on what future benefits will give you. But your brain doesn’t work like a spreadsheet.

Instead, you're navigating a complicated mix of emotions:

• Loss aversion — the pain of loss outweighs the joy of gain, so you hold on too long.

• Fear of waste — quitting feels like admitting all that effort was pointless.

• Identity and pride — you made the choice, so you must see it through.

And suddenly, logic takes a back seat.

4 Ways to Break the Sunk Cost Cycle

Here’s the twist: awareness isn’t just half the battle—it’s the launchpad for better decisions.

1. Reframe the “loss”

Stop thinking of time, money, or effort already spent as something you must justify. Instead, see it as data. What matters now isn’t the past; it’s whether continuing generates future value.

2. Evaluate with future focus

Before investing more, ask:

• What will this give me going forward?

• What opportunities am I missing if I stay stuck?

If the answer doesn’t measurably improve your life or goals, it’s time to reconsider.

3. Use data and deadlines

Set benchmarks before you start something. When outcomes don’t meet them, you’ve created a built-in exit strategy that doesn’t feel like giving up.

 4. Practice detachment

Not every investment must lead to a payoff. Letting go doesn’t erase effort—it frees you to invest in something with real upside.

Subscribe now to receive a Neuro Nugget delivered to your inbox every Friday!