In short
The sunk cost fallacy is the tendency to keep investing in something because of time, money or effort already spent. People continue even when stopping would be the better choice. Past costs cannot be recovered, yet they still shape decisions. It is a well-known cognitive bias in behavioral economics.
Why it matters for apps
Users weigh what they have already put into an app. Progress, history and earned status make leaving feel like a loss. Products often benefit from this, but it needs care.
- Stored value: Levels, badges, currency balances and history make the app more personal and harder to walk away from.
- Make investment useful: Effort should also make the product better for the user, such as better recommendations or a richer profile.
- Ethical line: Keeping users only because they fear wasting past effort breeds resentment. They stay, but they do not enjoy it.
- Common mistake: Wiping progress to force activity. Harsh resets can push users to quit instead of returning.
Industry examples
A Duolingo learner with a long streak keeps practicing partly because breaking it would waste the days already invested.
A banking app shows a user's tier status and points history, so switching banks means leaving that earned status behind (hypothetical).
Build it with StriveCloud
In StriveCloud, levels, XP, loyalty tiers, badges and virtual currency balances let users build visible value over time. Keep that value useful by letting users spend currency in the reward store, not only collect it.
Want to try this? See the loyalty solution
Frequently asked questions
What is an example of the sunk cost fallacy?
Finishing a bad movie because you already paid for the ticket. The money is spent either way, but the past cost still drives the choice.
How do apps use the sunk cost fallacy?
Apps let users build progress, status and history. Leaving then feels like losing that investment, which encourages users to stay.
Is using the sunk cost fallacy in apps ethical?
It is fair when the stored value also helps the user. It turns manipulative when users stay only out of fear of wasting effort.