See above.
Hint: that is only true if you denominate returns in DRK
The term Ponzi scheme refers to a very specific type of scam. One where current investors' gains are paid from funds contributed by new investors. Are you somehow involving inflation?
I'm using the term in a broader economic sense.
Note, however, that the literal defintion applies in some ways when you realize that the value of a coin where new coins are being created will not decline automatically by a given inflation rate. It will decline instantly to zero if no new capital is being added.
EDIT: somewhat does not apply to PoS coins where the new coins go to existing coin holders; those are closer to merely being inflationary.