I saw this picture on fb, and there's been a lot of such "First world problems" photos going around recently. So I gave it some thought.
The problem probably is that we're all longing for something greater (there isn't really any limit) and we do feel that we have the opportunity to do so. You could say it's the fear of complacency too, and that's probably why I do feel the same way, about being unhappy/dissatified despite whatever I have. We're not brought out to be satisfied with what we have currently, otherwise we never progress. Students get 95 marks and they want 100. Then they get 100 and want to make sure they're the only ones to get it (being the top of the top). I wouldn't say that after getting so many good things, we're "NOT HAPPY AT ALL". Surely deep inside there is a joy and gratefulness that we're good. But we tell ourselves and act as if we're "NOT HAPPY AT ALL", so that we can strive for something even greater. Otherwise, where is the motivating factor????