Someone being a billionaire is often considered immoral because in order to amass that much money, they basically have to exploit/underpay a bunch of people below them in a hierarchical environment.
But what about artists who are able to produce a functionally unlimited number of their creation, like a digital song, or an e-book? Could someone theoretically make something that got so popular and made so much money, that they could morally accumulate a billion dollars?
This thought experiment came up in a conversation a while ago, and I'd love to hear some other people's opinions.