We seem to have an inability to recognize when enough is enough. We think more will do the trick, even though it never does.
We always want more. People who don't aspire to have more are seen as dangerously unmotivated and potentially mentally ill.
But wanting more always leads to wanting more with contentment remaining frustratingly out of reach just ahead after the next purchase. We know this route is a dead end, but it doesn't stop most from pursuing it.
Kin Hubbard recognized the difficulty of it all when he said, "The hardest thing is to take less when you could take more."
I think real success is knowing when to stop and be content with enough.