Your calculations are straightforward, but the usage is not proportional to the price of a bitcoin because the price of electricity is not inelastic. As the usage goes up, the cost of electricity will increase more quickly.
BTW, you can do exponents like this: 2e
Agreed. That is why I said "trend to" perhaps "try to use" that much power would be better since, as you point out, prices would adjust.
Thanks. Fixed the typos in all my exponents.