[mcjshciejebcu]

I would expect visa to need more employees to maintain their systems, but that's just my intuition, and it might be wrong. You're right, too. Even though humans are very resource intensive (they need > 2kWh of energy per day), they're unlikely to outweight many orders of, magnitude difference.

I'd like to see an estimate of visa's energy usage using the same method the source you linked used to estimate bitcoin's energy usage. Take visa's revenue and multiply it by some fraction of revenue used for energy use (they used 52%). Some very rough calculations I did put it about 1000 times more energy expensive than visa's own report. That's still 1000 times better than bitcoin, using the same method, but it'd interesting to know where the discrepancy comes from, and whether that should also be considered for bitcoin's energy use.