Cost something like 120KWH of electric just to confirm a single transaction
Check your math. You seem to have made an error in that calculation.
That electricity is being used for much more than just "confirming a single transaction".
Do you mean in the philosophical sense?
If the actual, it's not too far off. Rounding some numbers:
Current network hash rate = 13.4 EH/s
13.4 EH / 14 TH per S9 = 960K units
960K * 1.4 KWatt = 1.34 GWatt
Average block time = 1/6 hours
Average transactions per block = 3000
1.34 GWh / 6 / 3000 = 74 kWh.
I assume not everyone uses the S9, so let's add 25% to get 90 kWh/tx.