Which do you think uses more computing hardware, every Bitcoin miner in the world, or the VISA payment network? Even today, the answer is quite clearly the total Bitcoin mining network--now consider expanding the scale of Bitcoin transactions to the VISA network, a 1000× scale increase.

Almost by definition, cryptocurrency requires spending useless energy. In electronic transactions as they exist today, you essentially only have to update the tables in two institution's databases (plus all the replication and backups that entails). A cryptocurrency requires everybody to record their transaction--and do a bunch of useless cryptography to to ensure that they do so.

Asking how much emissions it costs to mine the gold or grow the cotton to satisfy my paycheck is misleading. Exactly 0 joules were spent: no gold needed to be mined, nor coins minted, nor dollar bills printed to satisfy the electronic transactions to decrement a number at my employer's bank and increment the number at my personal bank appropriately.