The market is not some independent external arbiter. The market is based on rules government creates. Those rules can be exploitative - It may be perfectly legal to make payday loans to financial illiterates, or treat animals cruelly in meat plants, or simply to use marketing in a way to manipulate people's behavior subconsciously (which almost every company does).

Everyone who makes a billion dollars must attribute that success to themselves, but also the people who built the roads their product is delivered with, the teachers that taught them in school, the doctors that keep them healthy, etc.

What fraction of the wealth earned by a billionaire society is entitled to for its contribution will always be a fair policy debate.