Of course there is a limit. That limit is profitability:
Total mining reward == total electricity cost + hardware write off.
IOW,
total electricity use per hour == ~3600 BTC / (Price Kw/H + hardware write off per hour).
Add any mining fees to that 3600 if you want, and divide by 2 for each block reward halving.
In reality over time hardware write off will become a non factor, and average electricity cost in BTC will be the only variable that will determine the overall electricity use of the bitcoin network.
No cycles or moons involved unless both electricity and hardware would be free, in which case you get div/0 or infinity.
Dude why are you always using wring numbers? Only 250
BTC per hour are generated, a bit more if the network speed is on the rise, slightly more because of fees, okay let it be 300
BTC/hour, so for power price of 1
BTC/MWh it would be just 300 Megawatts.
M2 money supply = $10,789B
Bitcoin market cap = $1.576B
10786/1.576 ~ 6846x
Today's price ~ $120
6846 * $120 = $821,543
Assuming (incorrectly) that the only fiat that can be displaced is the US dollar.
Times 1.36M a year, divided by avg $0.10/kW (It'd be much cheaper if you put the bitcoin hardware at the powerplant to avoid transmission losses)
1.36M * 821543 / .1 =1.117 e13 kW-h per year
About 8766 hours a year
1.117 e13 / 8766 = 1274582135 kW = 1.274 TW
That is an ecological disaster. Not to mention dirty, nasty sources of electricity will be used in an attempt to bring down the cost per kW-h (which will result in an increase in the total watts needed for equilibrium).
And you, why are you comparing market supply with market capitalisation? You should either compare
BTC money supply with $ money supply (but with
BTC the money supply works differently so hard to compare), or
BTC market cap to $ market cap (that's what I did).
But then even if whatever you say is ridiculously true then nobody really cares, the green ecocentric scum uses leftist governments every day to slow progress and raise costs for everyone, maybe at least with
BTC they will suck because governments cannot defend them and their phony propaganda.
We'll use as much energy as we can afford, and we'll generate as much as we need, no way to change that.