What distinguishes a Ponzi scheme is that it promises returns that are paid out with money from new investors. What makes it a fraud is that the source of these

What distinguishes a Ponzi scheme is that it promises returns that are paid out with money from new investors. What makes it a fraud is that the source of these returns is misrepresented. It is mathematically doomed to fail eventually. A commodity like cryptocurrency (or precious metal) doesn't have returns. It may appreciate, depreciate or maintain its value. If the only argument for its appreciation is that "some bigger fool than me will find it to be more valuable", then that still does not make it a Ponzi scheme, nor does it make it a fraud.