Diderot Effect
One nice thing makes everything else look like trash. That's how a robe bankrupts you.
Grounded in the research on Diderot effect (Wikipedia)
The robe that broke Diderot
In 1769 philosopher Denis Diderot got a gorgeous scarlet dressing gown as a gift. Suddenly his old desk, his chair, his prints, his whole study looked like garbage next to it. So he replaced all of it and went into debt. He wrote about it in the 1769 essay 'Regrets on Parting with My Old Dressing Gown.' Anthropologist Grant McCracken named the pattern the Diderot Effect in 1988.
Why one buy triggers ten more
McCracken's mechanism: your possessions form a 'Diderot unity' a set of objects that share a consistent cultural meaning and signal who you are. Add one item that doesn't match the unity and you feel friction. To resolve it you either reject the new thing or upgrade everything else to match it. The new item resets the reference point, so the rest of your stuff now reads as 'below standard.'