I'm finding the "positive sum" language around coins really misleading.

It's literally the opposite. If the way users make money from their content is when other users buy it, it's literally zero sum, financially. Not everyone can be making money, unless external capital is being injected from a another source (which is losing money).

strong disagree. this is only true if you believe the actual value of the content is $0, which I strongly believe is not the case (trillions of dollars of value has been created from that content). 

if you believe the content has value, then it's straightforward to design a system that's positive sum because there's an infite supply of creativity.