> do I care if crypto miners want to mine at night in west Texas when wind is generating energy and the wholesale cost is negative (I.e. there is really no marginal productive use for that generation)? Absolutely not.

This is complicated though because power grids can resell that slack capacity further away if there’s a persistent surplus and other users will notice (e.g. cheap power really incentivizes overnight EV charging or even industrial users expanding). If all of the slack is being used for unproductive purposes, those positive feedback cycles will be delayed – unlike useful work, there’s no end of cycles which bitcoin mining can use so the potential power consumption is effectively infinite.