I disagree. You are right that the characteristic of a ponzi is that funds from new investors are used to pay existing investors.

But that is also a characteristic of crypto. You cannot buy anything for crypto without exchanging it for fiat, and for that you need a new investor to give you fiat for your cryptos. If all exchanges (incl. informal ones) close tomorrow, any crypto you hold is worthless.

Now, you could say that the same holds true for shares or real estate. But that is wrong. You can hold shares you bought ad infinitum, even if all stock exchanges close tomorrow, and would still receive your money's worth (approximately) in the form of dividends of the underlying company, or proceeds from the sale of said company, without ever selling those shares. You can live in a house or rent it out, and get your money's worth, without ever selling the house to someone else.

I don't see how you can get your money's worth with crypto without ever selling it to someone else.