Imagine you have an old smartphone you want to sell for 150 euros. A potential buyer says, "I will pay 80 euros at most," and you immediately think, "That is far too little!" Yet you would never have paid 150 euros for a used device yourself. Or a colleague suggests a better solution for your project, but you cling to your own idea, not because it is objectively better, but because it is "yours". This overvaluation costs you money, time, and sometimes even relationships.
I have worked with cognitive biases for years, and I see the endowment effect everywhere: when people sell old things, work on projects, and manage relationships. Research clearly shows that people value their possessions at an average of twice as much as objective buyers do, often without realising it. Whether you are selling your car, leading a project, or discussing an inheritance, this mechanism can show up anywhere.
The good news: you are not greedy or irrational when you overvalue what you own. The endowment effect is an evolutionary mechanism that affects us all. It helped our ancestors protect their resources. The difference is whether you recognise it and can adjust before making poor decisions.
In this article, you will learn what the endowment effect is and why it can be so strong. I will show you concrete examples from work, relationships, and everyday life. You will also get practical strategies to assess your own ideas and possessions more realistically and make better decisions.
What is the endowment effect?
The endowment effect describes how people greatly overvalue things they own. Once something is yours, you want more money for it than you would pay yourself. Research shows that sellers often ask for twice or three times what buyers are willing to pay.
A classic research example: students were given either a coffee mug or chocolate. Then they were offered a chance to trade. Although both items had the same value, 90% did not want to trade. They valued their own possession more highly than the alternative simply because it belonged to them.
The surprising part is that the effect can occur even with temporary ownership. If you get a test drive or try a product, its perceived value can rise straight away. Companies use this deliberately: free samples and trial periods create an emotional attachment before you even buy.
Why do we overvalue what we own?
The endowment effect has evolutionary roots. Protecting resources was vital for our ancestors. Anyone who gave away food or tools carelessly was at a disadvantage. That is why our brains developed a strong emotional attachment to possessions, even if it seems irrational today.
Once something belongs to you, your brain activates loss aversion. You feel the pain of a possible loss more strongly than the pleasure of an equal gain. That helps explain why you ask 200 euros for your old bike even though you would pay only 100 euros for it yourself. Selling it feels like a loss, even though you are not objectively losing anything.
Another factor is emotional meaning. If you own a gift from your partner, its perceived value rises. Not because of its quality, but because of the memories attached to it. Your brain links the item to positive feelings and overestimates its market value.
Everyday examples
Imagine you are working on a project and have an idea you really like. When your colleague suggests a better alternative, you ignore it. Why? Because your idea is "yours". You value it more highly, even though it is objectively worse. The team argues, deadlines pass, and you do not even notice that you are blocking yourself.
Or your family discusses selling the old family home. As someone who has lived there for years, you ask for 20% above market value. Your siblings see only the location and condition. They think you are greedy. You think they do not understand its emotional value. An appraisal would help, but you reject it because you believe your judgement is objective.
Another example: you inherit shares from a relative. They do not fit your investment strategy, but you hold on to them because they are now "yours". You value them more highly, ignore better alternatives, and lose returns. Your attachment to what you own costs you money, but you do not notice it.
Even small things can trigger the effect. Your friend borrows your old game controller and loves it. When they return it and offer to buy you a new one, you suddenly ask for three times the price. The controller has not improved. It belongs to you, and you do not want to let it go.
Without and with awareness of the endowment effect
Without awareness: You try to sell your 30-year-old car. You ask 20% above market value because you have driven it for years. Buyers turn you down. Months pass, the car stays in the garage, and costs rise. You think buyers do not understand its value, but you are overvaluing it emotionally.
With awareness: You get an appraisal, accept the real market value, and sell quickly. You invest the proceeds wisely instead of insisting on an inflated price. You recognise that your emotional attachment does not make the car more valuable.
How to deal with it
You cannot switch off the endowment effect, but you can counter it. Here are some practical strategies:
- Ask yourself: Would I buy this item or idea for the same price? If not, you may be overvaluing it. Compare it with real alternatives, not with your feelings.
- Get outside opinions: Appraisers, friends without an emotional attachment, or colleagues may be able to give a more objective view. Their perspective can show you where you are overestimating.
- For your own ideas: Ask others to assess your plans before you commit to them. Ask, "What would you do differently?" This reduces blind spots.
- For investments: Define your strategy first. Then check whether what you own fits it, not the other way around. This helps you avoid holding investments that do not fit just because you inherited them.
- In relationships: Change your perspective. Ask yourself, "How would I see this if it did not belong to me?" This can help with disagreements about selling a house or making shared decisions.
What to take away
- The endowment effect makes you value your possessions and ideas twice as highly as objective outsiders do.
- It made evolutionary sense, but today it can be irrational and cost you money or opportunities.
- It can affect anything that is "yours": objects, ideas, and investments.
- Ask yourself, "Would I buy this for the same price?" and seek outside opinions.
- Try this week: assess something you want to sell or give up from a buyer's point of view.