First, humans exchanged commodities. You could eat it, burn it for energy, modify it to create tools or jewelry. You exchanged something useful for something useful.
* It was energy.
Then, humans exchanged commodities for gold. You couldn't eat it or burn but it was still possible to modify it.
* It was poor energy.
Then, humans used papers checks or bank notes. It wasn't very useful, but you still could burn it during a very cold winter.
* It was very poor energy.
Now, we wants to use Cryptocurrencies. You can't do anything with it.
* It is not energy but proof of destruction of energy.
Something looks wrong. We should exchange potential energy, not destroyed energy.
Whether it is in a form of fiat or digital, I don't think we are wasting of energy to it. Currency is really helpful in our economy. It helps us to measure the trade either in import or export. Currency serves the treasure of the government and state. It use to give us a fair trading of goods or services. We got a lot of benefits from currency. So, don't underestimate it. Wasting of energy are those people who use it in a non-sense thing such as online games, videoke and etc. just to fill up their leisure time. We can't say it wasting of energy if it really helpful in our society.
Energy and discovering other source is basically and indication of technological advancement so how come crypto currency a waste of energy? is it just from mining? well energy I think is not a problem here for it is a part of our daily life and soon in the future humanity will have a new form of energy that makes nuclear and oil extinct. Currency is a power therefore we can't abolish to use energy to mainten its stability much more on crypto currency.