My wife uses this space heater during the winter. It does not mine bitcoin.

The way I see it, the energy spent on heat is a fixed cost. Any sats back from the S9 heater are a rebate kind of like how I got a rebate from the Oshi App when I bought the case.

I don't expect to get my sats back on my heater. It's not an investment. I expect to lose sats if I look at it that way. If it's a rebate, however, the sats are free.

I'm not doing it for the money. I'm doing it for the game theory. If bitcoin mining becomes unprofitable from a fiat perspective, who will run miners?

We'll need to find other ways to keep the hashrate high enough to prevent 51% attacks.

Energy used on heat that would be spent anyway is free bitcoin so the cost doesn't matter.

As the block rewards get smaller and smaller, I think mining pools will make less and less sense and yolo solo mining becomes more important. It's not profitable from an EV calculation, but people like to gamble. Lotto tickets are -EV, but states have no problem selling them.