Let's take an article [0] produced by a big Bitcoin miner at face value. They claim the banking system consumes 263.72 TWh globally, twice the power consumption of the Bitcoin network at that time, 113.89 TWh.
Now, Bitcoin is processing 4.6 transactions/second [1]. VISA alone is processing 1700 transactions/second on average, with peak transaction rates claimed in the 24000/second [2]. Mastercard is similar, as are other payment processors.
Even worse, the claimed energy usage is for the entire banking system. This easily amounts to billions of daily transactions, but also many other services that Bitcoin doesn't even come close to offering: insurance, mortgages, credits, risk evaluations, escrow and many others. All this for a mere 2x the total energy expenditure.
We were discussing Bitcoin. The Lightning network is a completely different thing, with completely different guarantees of payment security/trust than Bitcoin (it's possible to steal money on the Lightning network, or to do denial of service attacks against nodes, by design).
Bitcoin hasn't replaced the banking system though, nor could it (or should it). A crypto backed finance industry would be a libertarian hellscape of consumer abuse.
