No, that assumption (emphasis added) is popular but utterly false.
In a Ponzi scheme, cash from new buy-ins gets FRADULENTLY reported to existing participants as dividends from the underlying business or investment.
That fraudulent reporting of fake-dividends is essential to the scheme, because it's how the scammer lures in successive waves of investors to keep it perpetuated.
Unsustainable optimistic speculation != Ponzi Scheme
It was conflated in the past because without smart contracts ponzi schemes were necessarily executed by people.
>Unsustainable optimistic speculation != Ponzi Scheme
Speculation on a token that doesn't generate any income and isn't backed by anything is one version of a ponzi scheme, yes.