What is the Sunk Cost Fallacy?
The sunk cost fallacy is a cognitive bias where people continue investing in something because of what they’ve already spent, not because of what they’ll gain going forward. In marketing, this shows up when brands keep funding underperforming campaigns, clinging to outdated strategies, or refusing to kill products that no longer serve the business. The rational move is to evaluate decisions based only on future costs and benefits. The emotional move is to protect past investments.
Most marketers choose the emotional move more often than they’d like to admit.
How the Sunk Cost Fallacy Works
Behavioral economists Daniel Kahneman and Amos Tversky identified the mechanism behind this bias through their work on prospect theory. Losses feel roughly twice as painful as equivalent gains feel good. When a marketer has spent $50,000 on a campaign that isn’t converting, walking away doesn’t just mean losing the future budget. It means admitting the $50,000 is gone.
That admission triggers loss aversion, and loss aversion triggers irrational escalation. The result: throwing good money after bad.
The fallacy operates on a simple but flawed logic chain:
- I’ve already invested significant resources (time, money, effort).
- If I stop now, that investment is wasted.
- Therefore, I should continue investing to justify what I’ve already spent.
The flaw is in step two. The investment is already gone regardless of the next decision. Economists call these sunk costs because they can’t be recovered. The only question that matters is whether the next dollar spent will generate a positive return.
Sunk Cost Fallacy in Marketing Decisions
This bias shows up in marketing departments at every level, from daily campaign management to long-term brand strategy.
Campaign Escalation
A paid media team launches a campaign with a $200,000 quarterly budget. After six weeks, the cost per acquisition is 3x the target. Rather than pausing and reallocating, the team increases spend, reasoning that the algorithm “needs more data” or that results will improve “once we hit scale.”
Sometimes that’s true. Often it’s the sunk cost fallacy dressed up in media buying language.
Product Line Persistence
Procter & Gamble’s former CEO A.G. Lafley made a career-defining move when he cut over 100 brands from the P&G portfolio between 2014 and 2017. Many of those brands had decades of investment behind them. The company had spent billions on R&D, distribution, and marketing.
But Lafley evaluated each brand on future growth potential, not historical spend. The result was a leaner portfolio that drove stronger margins.
Martech Stack Bloat
The average enterprise marketing team uses 91 different tools, according to a Gartner survey. Many of those tools were expensive to implement, required months of onboarding, and now sit underused. Teams keep paying the license fees because switching costs feel high and because abandoning the tool means “wasting” the implementation investment.
The implementation cost is already sunk. The only relevant question is whether the tool delivers enough value to justify the ongoing subscription.
Content That Nobody Reads
A brand publishes a 5,000-word whitepaper after three months of research, writing, design, and legal review. It generates 12 downloads in the first month. The rational response is to analyze why it underperformed and redirect effort toward formats that work.
The sunk cost response is to spend another $5,000 promoting it through paid distribution “because we put so much work into it.”
How Marketers Use the Sunk Cost Fallacy
While the fallacy can hurt internal decision-making, marketers also use it deliberately to influence consumer behavior.
| Tactic | How It Works | Example |
|---|---|---|
| Free trials with setup investment | Users spend time configuring the product, making them reluctant to cancel | Salesforce’s onboarding requires custom field mapping, workflow creation, and data imports |
| Loyalty programs | Accumulated points create a perceived investment that discourages switching | Starbucks Rewards members are 5.6x more likely to visit daily than non-members |
| Progress indicators | Showing users how far they’ve come makes abandonment feel wasteful | LinkedIn’s “Profile Strength” meter encourages users to complete every field |
| Subscription lock-in | Annual plans paid upfront make cancellation feel like losing money | Adobe Creative Cloud’s annual commitment with early termination fees |
Each of these tactics ties into the broader psychology of commitment and consistency. Once someone has invested effort, they feel psychologically compelled to continue.
The Kill Criteria Framework
The most effective defense against the sunk cost fallacy is setting decision criteria before the investment begins. In marketing, this means establishing clear kill criteria for every campaign, product launch, and strategic initiative.
- Define the threshold upfront. Before launching a campaign, document the specific metrics that would trigger a pause, pivot, or cancellation. “If CPA exceeds $45 after 10,000 impressions, we reallocate.”
- Use a pre-mortem. Ask the team before launch: “If this fails, what’s the most likely reason?” This makes failure feel less like a personal loss and more like an expected scenario.
- Separate the decision-maker from the investor. The person who approved the original budget shouldn’t be the only voice deciding whether to continue. Fresh eyes evaluate future potential more objectively.
- Track opportunity cost. Every dollar spent continuing an underperforming campaign is a dollar not spent on something that might work. Make the alternative visible.
Sunk Cost vs. Strategic Patience
Not every decision to continue investing is irrational. Some strategies genuinely require time to compound. Brand equity builds slowly. SEO takes months. Community growth is nonlinear.
The difference between sunk cost thinking and strategic patience comes down to one question: Is the decision based on evidence about the future, or emotion about the past?
If there’s a clear model showing how current investment leads to future returns, that’s strategy. If the primary argument is “we’ve already spent too much to stop,” that’s the fallacy.
Relationship to Other Biases
The sunk cost fallacy rarely operates alone. It compounds with several other cognitive biases that marketers should understand:
- Loss aversion amplifies the pain of writing off past investments.
- Confirmation bias leads teams to seek data that justifies continued spend while ignoring signals that suggest stopping.
- Anchoring ties expectations to the original investment size rather than current performance data.
- Status quo bias makes “keep going” feel safer than “try something new,” even when the numbers say otherwise.
Key Takeaways
- Past spend is irrelevant to future decisions. Evaluate every marketing investment based on projected returns, not historical costs.
- Set kill criteria before launching. Pre-committed exit points remove emotion from the decision.
- Audit your martech stack and campaign portfolio regularly. Look for tools, campaigns, and products kept alive only because of prior investment.
- Use the bias ethically in customer-facing strategy. Loyalty programs, progress indicators, and setup investment all create switching costs that improve retention.
- Distinguish patience from stubbornness. Evidence-based persistence is strategy. Investment-based persistence is the fallacy.
FAQ
What is the sunk cost fallacy in simple terms?
The sunk cost fallacy is the tendency to keep investing in something because of what you’ve already spent, rather than evaluating whether future investment makes sense. In marketing, it often shows up as continued spending on campaigns, tools, or products that aren’t delivering results.
How does the sunk cost fallacy affect marketing budgets?
It causes teams to over-invest in underperforming channels while underfunding new opportunities. When a significant portion of the budget has already been committed to one strategy, reallocating feels like admitting failure, even when the data clearly supports a change.
Can marketers use the sunk cost fallacy to increase conversions?
Yes. Tactics like free trials with extensive onboarding, loyalty point systems, and progress-based gamification all create a sense of invested effort. That perceived investment makes customers less likely to switch to competitors or abandon the purchase process.
What is the difference between sunk cost fallacy and loss aversion?
Loss aversion is the broader bias where losses feel more painful than equivalent gains feel good. The sunk cost fallacy is a specific pattern where loss aversion causes people to continue investing in losing propositions to avoid recognizing a loss. Loss aversion is the engine. The sunk cost fallacy is the behavior it produces.