It doesn't have to be competitive.

4+ kWh electric showers are ubiquitous in my country. Literally a dumb piece of metal resistance immersed in water. Anything is better than the current situation. What if it was a processor instead?

What if a bunch of home servers could heat up stored water through their heat instead of just dissipating that energy uselessly into the air?

We'd be getting the heat we need and we'd be helping build a decentralized cash network. We were gonna spend energy heating up stuff anyway. Might as well get some cryptocurrency out of that heat.