For Bitcoin to be secure, you always need more energy to be devoted to honest mining than is devoted to an attack -- and that ignores the energy spent securing Bitcoin wallets (which is fine to ignore, as it is tiny by comparison). In the limit, half the energy output of the entire planet would have to be devoted to Bitcoin for it to remain secure, though I doubt that any economy could sustain such a situation.
By comparison maintaining security for paper money requires substantially less energy than attacking paper money, even if you include the energy devoted to fighting theft (the analog of the energy devoted to securing individual Bitcoin wallets). The energy spent on counterfeiting detection is far lower than the energy needed to counterfeit modern paper money, and Chaum showed the world how to create digital cash that is even more secure against counterfeiting, with security against double spending, and that allows for anonymous transactions, while still requiring far less energy to be spent on security than would be needed to attack the system.
So no, there is no hyperbole here. Bitcoin is a very inefficient system. It might work in practice, but that does not make it efficient, nor does it even make it an improvement over what we have now. The only think Bitcoin has going for it is that there is no obvious central authority (I say no obvious central authority because in practice, the Bitcoin developers have as much power over the currency as a central bank -- they can e.g. cause a block chain fork at any time, as they accidentally did a few months ago).
By comparison maintaining security for paper money requires substantially less energy than attacking paper money, even if you include the energy devoted to fighting theft (the analog of the energy devoted to securing individual Bitcoin wallets). The energy spent on counterfeiting detection is far lower than the energy needed to counterfeit modern paper money, and Chaum showed the world how to create digital cash that is even more secure against counterfeiting, with security against double spending, and that allows for anonymous transactions, while still requiring far less energy to be spent on security than would be needed to attack the system.
So no, there is no hyperbole here. Bitcoin is a very inefficient system. It might work in practice, but that does not make it efficient, nor does it even make it an improvement over what we have now. The only think Bitcoin has going for it is that there is no obvious central authority (I say no obvious central authority because in practice, the Bitcoin developers have as much power over the currency as a central bank -- they can e.g. cause a block chain fork at any time, as they accidentally did a few months ago).