translation.en: And so the lesson is this: it doesn't really matter what you're selling; you just have to think about who is your customer, that are going to get them to change their behavior.
translation.zh: 因此关键在于： 你卖的是什么东西并不重要 你要考虑的是谁是你的客户群 以及让他们做出改变 的原因是什么