You don't need this amount of computing power to send messages. All that these processors do is guarding against 'double spending' - but 'double spending' is a

You don't need this amount of computing power to send messages. All that these processors do is guarding against 'double spending' - but 'double spending' is a peculiar problem of distributed cash - a centralized currency could be secure against 'double spending' without burning so much electricity.