I came across this theory today and wondered what you think about this - does ownership create more value, and if so, in whose eye?

THE ENDOWMENT EFFECT

“Simply put, the endowment effect shows that we value the things we own more than identical products that we don’t own. This causes a mismatch between buyers and sellers, where buyers are often willing to spend less than the seller deems an acceptable price.”

I've come across this recently listing my own property for sale.  I know all the work we put into the home - but did that work create additional value or did it bring the home to the values of the neighboring properties?  What are your thoughts?