Surely crypto has always been zero-sum? People put their money into the pot, and then take it out at different times, in proportion equal to when they originally put their money in.
Crypto seems to be negative sum, due to the large amount of equipment and energy expenses that go into operating the whole infrastructure. (Obviously this is technically true of almost everything, but in case of cryptocurrencies I think the relative operating cost is much higher than, e.g., stocks or bonds or casinos).
It depends on the currency, some have transaction fee mechanisms that pay existing holders, meaning there’s at least some amount of revenue (holders are selling transaction slots to transactors). Holding the currency is essentially a bet that revenue will increase