[aeternus]

True there is a lot of speculation today, and transaction fees are much too high to use for everyday expenses. I would say store-of-value is a valid use-case though. The ability of an individual to store wealth in their brain is a useful property. Mostly for those attempting to escape oppressive governments, or "extractive" political institutions.

The transferring of bitcoin is not what is energy intensive. The energy is expended as a "vote" on which of many possible forks should be trusted. Gold definitely has this expenditure as well, military's are often required to secure it, and large amounts of energy and expenditure are required to discover and mine it.

USD is one of the most stable currencies in the world, and the fed has done a good job of maintaining stability. You're right that Bitcoin is no where near as stable as USD, but it is more stable than the currencies of some other countries. There are still ways for a central bank to maintain interest rates even if Bitcoin is widely used. Bitcoin does not prevent fractional reserve banking.