Bitcoin uses less than 0.1% of the world's energy. Any time somebody says things like "uses more energy than a country" they are either dishonest or malicious and clearly have an agenda. I'd recommend to try to stick facts, not opinions.
Bitcoin or not I don't like the idea of having opinionated people and entities judging what I do with the energy I paid for. Today is proof of work, tomorrow might be high end computer gaming, hopping on a car for a trip etc. You can already see on this very site judgmental comments about carbon usage when you mention a hobby like home lab.
My initial point was to inform the OP about peer-reviewed articles on current waste, not which energy uses are allowed or disallowed, nor a call to judge or curtail individual energy expenditures.
As with many things, there is not a single 'right' or wrong, but degrees of evidence. Highlighting current chain inefficiencies allows future versions to better mitigate these energy impacts. Honing any process to use less energy while achieving similar or better results is not an unreasonable goal.
Re: your first point, am I right to understand that entities that are able to afford higher usage should have no qualms doing so?
> My initial point was to inform the OP about peer-reviewed
"Peer-reviewed" is meaningless if it's not scientific, fact-based.
> articles on current waste
See, you start with the assumption that it's wasted. You can only come to that conclusion if you assume that bitcoin serves little or no purpose.
> Honing any process to use less energy while achieving similar or better results is not an unreasonable goal.
Energy usage is what brought humanity from stone tools and caves to the moon, using energy is a good thing that advances civilization. Energy production can be problematic, which bitcoin doesn't do. Proof of work is one of the core innovations, there is no system that has better results.
I wouldn't be too quick to dismiss the linked sources, though. Similar to the authored pieces, I don't assume energy is 'wasted' on a perceived goal, but that actual waste is produced (e.g. mining devices are discarded quite frequently) as well as waste energy due to protocol implementation inefficiencies and infrastructural limitations (i.e. many compute cycles for little gain).
Both can be accounted for: would you not rather see a version where these issues are accounted for? PoS is a sure way forward, but there are still many legacy chains around that do not benefit from this [0].
Less than .1% to secure more than 500 billion of value. Bitcoin energy usage is primarily to secure the network, not for transaction "volume", but that's a common misconception for people who have yet to learn about bitcoin.
You're splitting hairs. If the energy is needed to stave away a 51% attack, that's the energy needed to support the single digit tps monstrosity you have. As for the 500 billion in value, I doubt if everyone liquidated their positions today it'd amount to a figure remotely close to that.
[0]: https://www.sciencedirect.com/science/article/pii/S092134492...
[1]: https://www.mdpi.com/1996-1073/14/14/4254
[2]: https://www.cell.com/fulltext/S2542-4351(19)30255-7