This planet has — or rather had — a problem, which was this: most of the people living on it were unhappy for pretty much of the time. Many solutions were suggested for this problem, but most of these were largely concerned with the movements of small green pieces of paper, which is odd because on the whole it wasn’t the small green pieces of paper that were unhappy.
The unhappy person resents it when you try to cheer him up, because that means he has to stop dwelling on himself and start paying attention to the universe. Unhappiness is the ultimate form of self-indulgence. When you’re unhappy, you get to pay a lot of attention to yourself. You get to take yourself oh so very seriously.