For society, by making the distribution of goods/services more efficient. Amazon enriches our lives (compared to no Amazon) every time anyone uses it. The resources we all save, the delta, go partially to Mr. Bezos and owners of Amazon stock in the form of profit. They are rewarded for having allocated their capital efficiently. They can spend the money on whatever they want, but it is mostly allocated back into making Amazon more efficient -- not locked away as the gp suggests.

Bear in mind this is the extremely idealistic neoliberal take.