A Ponzi scheme is a fraudulent investment operation that pays rewards to its investors from their own money, or the money paid by its subsequent investors.

Any financial markets can be involved in such activity, and it is the same for Bitcoin. But the main purpose of these financial markets including Bitcoin, isn’t the Ponzi scheme.

Also Bitcoin isn’t centralized and no one owns the community or controls it.

The fact that the internet created digital currency with value, seems very skeptic but it doesn’t directly lead to Ponzi Scheme.