You can view it in sort of geopolitical terms and say, why is it that a billion people on this planet are so desperately needy that they have no possibility of happiness, and whereas almost all the rest of them, regardless of how much money they have -- whether it's two dollars a day or whatever -- are almost equally happy on average?
你还可以从地缘政治学的角度来分析， 为什么地球上会有近10亿极其贫穷的人们 永远得不到快乐， 而另外其他的人， 无论他们有多少钱，两美金一天也罢， 其他数字也罢，快乐的感受都差不多？