Having equipment sitting around unused is way more expensive than most people care to think about.

A heating coil might not be terribly valuable in July, but come November it will have roughly the same value it had the previous February. Bitcoin mining hardware that's switched off for five months is losing value at an alarming rate, and very quickly won't be a net reduction in costs.

Very quickly a heat pump becomes cheaper to operate, and cheaper to purchase. And if you amortize the cost over the life expectancy, that threshold is very, very low. People who have recent memory of living paycheck to paycheck are constantly screwed by the latter, and that Venn diagram overlaps heavily with several other circles that make crypto super attractive to some people and super ridiculous to others.

I went down this avenue of compute as radiator long ago, and I could never get the math to work, unless I moved somewhere that was cold most of the year, and that sure as fuck is not going to happen.