I think so, but it is hard to say. Could be a lot of people with extra power (or stolen power), but their own equipment. I mine myself with waste solar power
If it's cold and you're going to be running a heater anyways, then if your heat is resistive, then running a cryptominer is just as efficient and returns a couple dollars back to you. It effectively becomes "free" relative to running the heater.
If you use a heat pump, or you rely on burning something (natural gas, wood, whatever) to generate heat, then the math changes.
Another option:
Deliberate heat generation.
If it's cold and you're going to be running a heater anyways, then if your heat is resistive, then running a cryptominer is just as efficient and returns a couple dollars back to you. It effectively becomes "free" relative to running the heater.
If you use a heat pump, or you rely on burning something (natural gas, wood, whatever) to generate heat, then the math changes.