So then it comes down to, we’ll is that extra processing these data centers doing useful or wasteful? And that’s all subjective. Some of its more clear cut probably: work that leads to new medicine probably useful. Work that hijacks dopamine processes to addict people. Arguably not useful. But how do we determine that fairly? And where would we draw a line on this kind of moral policing of energy use?
I still do think that it's an important difference whether becoming more resource efficient is something that could be incentivized/enforced without endangering the underlying business model or whether resource waste is the business model.
That only affects who finds the next block. It will always take about 10 minutes, regardless of hashrate, energy usage, hardware efficiency, number of miners, etc. since the difficulty is adjusted to factor all of those out.
For anyone who isn't a miner (and doesn't care to become one), the only variables which matter are energy-usage and difficulty-of-51%-attack (i.e. double spending).
AFAIK the only reasons to advocate for bitcoin mining are:
- A vested interest. Since bitcoin is a zero/negative-sum game, nobody else should care about someone else's vested interest; if anything they should be opposed (in the negative case; e.g. as a waste of shared resources).
- belief that double-spending is currently unacceptably easy, and would become acceptably difficult given the increased hashrate.
Whilst I don't know of an objective 'acceptable optimum' for the difficulty of double-spending, it would take a lot to convince me that (a) there are credible threats given the current hashrate and (b) those threats would be solved by an increased hashrate. The only threats that even come close would be on the scale of nation-states, or perhaps the largest tech multinationals; yet even if we're paranoid enough to believe they could pull off an attack, I fail to see how burning even 10 times as much energy on hashing would disuade such a level of paranoia.
If you hold the hardware constant then hashrate correlates to energy usage obviously, but it's not quite the same thing.
As long as the total hashrate is "cheaper" than that, in terms of hardware and electricity costs, there is an economic incentive for somebody to start mining (more) – so somebody will.
Data centers would jump at the opportunity of using 50% less electricity due to more efficient processors. Bitcoin miners would just mine twice as fast.