They are coupled, but the BTC price is the independent variable, because of the difficulty adjustment. If the price rises, the mining becomes more profitable,

They are coupled, but the BTC price is the independent variable, because of the difficulty adjustment. If the price rises, the mining becomes more profitable, more miners jump in, and mining gets more difficult so the issuance rate stays roughly constant. If the price falls, mining becomes less profitable, some miners drop out, and to keep issuance from slowing down the difficulty is decreased. Whatever the price does, the energy usage follows. So we can't really say that energy usage is the foundation of BTC's value, it's the other way around.