I do not think cryptocurrency can be considered a ponzi scheme. The ponzi scheme is based on a certain centralization, while the crypto market is totally decentralized. If coin prices are very fluctuating during this period, it does not mean it has anything to do with the ponzi scheme. Simply, investors are expecting a higher decline in currency prices.
Some of them say that bitcoin is only profitable for old users, but we reject it. I as a new user also benefited and it's true what you
say, Bitcoin is decentralitation, that system is far different from the ponzi scheme