[jafaku]

> credit card transactions are in fact far more energy-efficient than bitcoin transactions

Huh? You seriously think Visa/Mastercard are using less energy than Bitcoin?

> Furthermore, there will be an energy cost to transactions even after no substantial number of bitcoins are mined, since just verifying transactions requires wasteful hashing.

You can call it wasteful all you want, but if you don't see the value in creating/maintaining a global framework for storing and exchanging value, then I don't know what to tell you. Besides, you are comparing apples to oranges. Bitcoin is a currency. You can build things like Visa around Bitcoin.