>wear on mining machines There is virtually no wear on mining machines from actual use. There is, but it's negligible compared the main cause of depreciation of mining machines: better hardware coming out every 2-4 years AND the reduction in mining reward rate[1]. A bitcoin mining rig is worth essentially 0 after 2 years due to this depreciation. Not failure from wear. This is also true for GPU miners.

Second, there are many better uses for cheap power - one could use it to store energy in a hypothetical future where we use lots of intermittent renewables. You could use it to produce highly energy intensive physical goods - aluminum, hydrogen gas, fertilizer. You could use it for intensive climate engineering with carbon capture.

Almost anything else you can think of would be better than running a proof-of-waste cryptocurrency network.

[1] https://paulbutler.org/2022/the-problem-with-bitcoin-miners/