Because what that question assumes is that our external world is predictive of our happiness levels, when in reality, if I know everything about your external world, I can only predict 10% of your long-term happiness.
因为这个问题假设 通过外部条件是可以预测我们的快乐程度的 但实际上，如果我了解你所有的外部条件 我只能预测你长期快乐程度的10%。