The IKEA effect

Every time we create something whether it's a child or piece of IKEA furniture there is a high chance that we overvalue it. We fall in love with it and become attached to it.

The effort that we put into something does not just change the object. It changes us and the way we evaluate that object. Interestingly greater labor leads to greater love. Has anyone asked you to look at her children's photos as they are the cutest things on earth? And then you were dying for that boring slideshow to finish.

Our overvaluation of the things we make runs so deep that we assume that others share our biased perspective but most of the time they don't. They just don't.

We spend hours to assemble a piece of IKEA furniture and take pride in it as our own creation and art but most of our friends may look at it just as a cheap IKEA furniture.

Paying more for less
The joy of work
The not-invented-here bias
The case for revenge
Why we get used to things
The long term effects of short term emotions
and The IKEA effect are some irrational behaviors we have and Dan Ariely has written a very insightful book about them which is called "The upside of irrationality", I highly recommend  it.