It started innocently enough. I bought a new desk.
My old desk was scratched and wobbly, so I bought a beautiful, sleek, white minimalist desk from IKEA. It cost $150. I felt like I had made a “Smart Price” decision.
But when I set up the new desk, I noticed a problem. My old, dusty black chair looked terrible next to the clean white desk. It ruined the “vibe.” So, I bought a new grey ergonomic chair ($300).
Then, I sat down. I realized my old, clunky mouse pad looked ugly on the new surface. And my computer monitor looked yellow compared to the bright white wood. Within two weeks, I had bought a new chair, a new monitor, a new mouse pad, and a new lamp.
The $150 desk project had spiraled into a $2,000 office renovation.
I wasn’t being stupid. I was a victim of a psychological phenomenon known as the Diderot Effect.
Here is why buying one new thing often triggers a chain reaction of spending, and how to stop it.
1. Who Was Denis Diderot? (The Story of the Robe)
This effect is named after the French philosopher Denis Diderot. In the 18th Century, Diderot lived a humble life. One day, a friend gave him a gift: a beautiful, expensive Scarlet Robe.
Diderot loved the robe. But when he wore it in his messy, dusty apartment, he felt uncomfortable. The robe was too elegant. It made his old rug look ragged. It made his wooden table look cheap.
So, Diderot started replacing things. He bought a new rug from Damascus. He bought expensive sculptures and a new mirror to “match” the elegance of the robe. By the end, he was broke.
He wrote an essay called “Regrets on Parting with My Old Dressing Gown.” In it, he wrote:
“I was the absolute master of my old dressing gown, but I have become a slave to my new one.”
2. The “Apple Ecosystem” Trap
In 2025, tech companies weaponize the Diderot Effect. They design products that look wrong if you don’t own the matching set.
Let’s say you buy a new iPhone 16.
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Suddenly, your old wired headphones feel “outdated” because the phone has no jack. So, you buy AirPods.
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Now that you have the AirPods and the Phone, your old Fitbit watch looks clunky. It doesn’t “sync” perfectly. So, you buy the Apple Watch.
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Now you have the Phone, Watch, and Earbuds… but your old Windows laptop can’t send iMessages. So, you buy the MacBook.
The first purchase (The Phone) created a psychological “gap” in your identity. You spent the next $2,000 trying to close that gap so everything felt “complete” again.
3. Why It Happens: “Identity Coherence”
Psychologically, humans crave Coherence. We want our environment to match our identity.
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If you see yourself as a “Gamer,” you can’t just have a gaming PC. You need the RGB lights, the mechanical keyboard, and the streamer microphone—even if you don’t stream.
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If you see yourself as a “Fitness Person,” buying new running shoes makes you want to buy the matching shorts, the water bottle, and the Strava subscription.
We aren’t buying products for their utility. We are buying props for the “character” we are trying to play.
4. How to Break the Chain
The Diderot Effect is hard to resist, but not impossible. Here are the three rules I use to stop the spiral.
Rule 1: The “One Month” Quarantine When I buy a new significant item (like a phone or a couch), I forbid myself from buying any accessories for it for 30 days.
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This forces me to get used to the “mismatch.”
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Usually, after 30 days, the urge to “match” everything fades away.
Rule 2: Buy Isolated Items I try to buy things that fit my current life, not my fantasy life. If I buy a new shirt, I make sure it matches the pants I already own. If I have to buy new pants just to wear the shirt, I don’t buy the shirt.
Rule 3: Embrace the “Frankenstein” Setup Look at the most productive people in the world (coders, writers). Their setups are often messy. They have mismatched monitors and old chairs. Why? Because they are focused on Output, not Aesthetics. A matching desk setup doesn’t make you work harder. It just makes you poorer.
Conclusion: Don’t Become a Slave to Your Stuff
Diderot was right. He became a slave to his robe. Don’t become a slave to your iPhone or your new car.
The “Smart Price” is realizing that your old stuff is perfectly fine. The mismatched rug, the scratched desk, the older headphones—they tell the story of your life. Don’t replace them just because a new item made them look “old.”