By that rational, any publicly traded commodity is a ponzi\pyramid scheme. Anything with a finite supply and demand will command a price. The market doesn't care if you dislike the speculative nature of bitcoin; it is simple supply and demand at work.

You could make the exact same arguments against gold but that doesn't stop central banks of the world from hording it: https://en.wikipedia.org/wiki/Gold_reserve The only differences are 3,500 years of history and... teleportation.