To buy the new fashion item or the new gadget, etc is to be unhappy with what you already have because it is not the new thing being sold to you. That is what it boils down to. This comes from the story told by those selling things to us that what they are offering will make us happy. This cannot be true if the last thing they sold us, which is now out of fashion or less up to date, also was supposed to make us happy.
It is better to try and be content with what we already have. Otherwise we will be leaping from shiny object to shiny object and never really being happy, just momentarily joyful.
The Fullfilment Project 