Except that bitcoin fits none of the definitions of a ponzi scheme, unless you think money as a technology for storing wealth is a ponzi scheme.
For example, under the gold standard (1870s until 1913), the US saw gradual price deflation, meaning people expected their money to gradually grow in purchasing power, yet (amazingly) the economy grew! Turns out deflation isn't bad, even thought it may look like a ponzi to those who don't understand it.
Ponzi schemes are wack, and you can still find people who think they too can become hundred-millionaires by putting a few hundred into bitcoin