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).

seeing how remnant user holdings get rounded down to zero, forgotten to atrophy and rot into worthless dust clogging the bottom of all our wallets, i might even argue it's actually negative sum