I don't like this argument. It's garbage. Bitcoin does not replace the functions of the entire financial system. I can't take out a loan using the blockchain. Banks do far more then act as a ledger. Bitcoin's utility today is a little more than P2P value transfer. A centralized solution - something like Transferwise - does not use as much energy as Bitcoin.
Then your choice comes down to this: Use a centralized system for less energy consuming transaction but greater centralization of wealth -- or -- Use a distributed system that requires more energy but distributes wealth amongst network participants. Personally, I would choose the system that distributes wealth at the expense of additional energy cost. Ideally, I would choose the system that distribute wealth and has the least environmental impact.
I'm not in a position to estimate the waste energy of a financial institution either, but you're right that it probably is quite large, but it's hard to say which is more wasteful.
But let us assume that all those thousands of financial institutions and their associated infrastructure are just there to handle transactions.
Bitcoin is doing about 20 tx/s and Bitcoin mining uses as much energy as the nation of Denmark.
Visa is doing about 1700 tx/s.
> Renewables! Almost free, unlimited energy!
Oh man, I should have been reading your last sentence a bit better. With all those cryptomaniacs my sarcasm detector is a bit confused.
combine the tx/s of all the cryptocurrencies out there right now and I assure you it exceeds Visa's 1700 tx/s. NOT ALL TRANSACTIONS HAVE TO HAPPEN ON THE BITCOIN NETWORK! There are thousands of coins!
Also Visa is only just one company, there are also Master, American Express, Paypal, SEPA transactions and a lot more.
So I don't understand what you try to tell me and how screaming improves your argumentation.