The whole "ponzi scheme" accusation is trotted out every time Bitcoin is brought up, and it's always by people completely unfamiliar with how Bitcoin actually functions. It's as much a "ponzie scheme" as much as any other limited-supply asset.
the only real value it currently offers, is it allows people to dodge tax and launder money. it also enables the criminal economy, with things like drug-ecommerce when the government does not approve (im all for legalisation, btw). so it undermines goverment authority and enables criminality.
i get that i get downvoted because people here believe strongly in privacy and tend to dislike their governments. but i don't. you have to think about how much of your life depends on government authority in order to understand the danger anything that undermines it poses.