My understanding of a ponzi-scheme is that you subscribe with an initial capital with a regular currency; and then you expect regular payouts in that same currency. The regular payouts pay a lot comparing to what the market pays for no-risk assets.
Hence why I generally try to say Ponzi-like scheme. It doesn't fit exactly. The bad actor in a Ponzi scheme, the single issuer would be the stock broker, however in the case of a crypto-asset would be the crypto-asset itself, e.g. Bitcoin, Ethereum's Ether. And then there are the owners of those assets who are doing the promoting to get people to adopt it and hoping people will pay X amount more for it than they paid. This is too shallow of an explanation anyhow. I believe I have left longer comments relating to it on HN, though they may not fully describe all of the problems with it.
I don't think bitcoin fits that definition.