If you earn more, you pay more in tax, so it's all swings and roundabouts.

赚的越多，缴的税也越多，所以有得必有失。

Whatever the outcome of all these swings and roundabouts along with many more, the reason that deciding what to do with your life is so difficult is that it involves predicting the future.

不管上述列举事情的结果如何，不管这些事情周围还有多少其它事情，让你决定生活中应该做什么事情很困难的原因，是因为你必须去预测未来。