Cryptocurrency is by definition, an open transparent market and as such not a Ponzi scheme. Quite literally by definition.

Also many of the current cryptocurrencies run on tiny amounts of energy (Algorand, Cardano).

Some of the brightest minds in applied mathematics and cryptography are working on this stuff. Maybe you should be a little more open minded.

Edit: downvoted without any discourse. This site is so strangely anti crypto, stay smug, let’s see how it works out for you.