So, what you're basically saying is that bitcoins, USD, gold, silver, wheat, salt, rice, beef, pork, etc, are all Ponzi schemes.
This.Bitcoin is comody now, which might be in future used as currency. Its like collectable goods, minimal real value, but high expectations and thus high price not a Ponzi.
It might very well be a bubble, but not a Ponzi. Ponzi should be used with centralised schemes where early investors are paid by later. Pyramid is bit more complex. As nothing is paid out, it can't be Ponzi.