I would argue that the benefit of decentralization is not worth the price.
If all the super computers on the world started mining Bitcoins, it would take them 10 minutes (or so) of calculation to mine a block. The 10 minutes are fixed, it doesn't get faster even if you get faster computers. Just the power waste gets higher.
Every 2016 blocks the difficulty adjusts so that ON AVERAGE a block is found every 10 minutes. If the hashing power of the network is increasing over time, the amount of time it takes to find a block goes down (can be less than 10 mins) as it approaches the next difficulty adjustment (and vice versa).
But you are correct that as the hash rate increases, the total power consumption increase along with it -- at the moment there is no proven alternative.
You're incorrect to state that crypto is "controlled by a much smaller number of unaccountable people" -- Bitcoin and Bitcoin Cash are decentralized networks with lots of different stakeholders (miners, developers, exchanges, wallets, users) and no single group is in control. Quite the opposite -- there has to be broad consensus among all the groups for a cryptocurrency to survive long term. Not possible to fork your own currency off of the USD or the EURO!
I still fail to see how bitcoins would let us get rid of either crime or war, nor downsize the army or LEOs.
Same for the "conventional power politics", it's hardly a new thing, put a 100 random people on a island and you'll see the same mechanisms at play.
If a currency were to arise with no political group can control, this mechanism of domination would be short-circuited. I don't doubt that there would still be organized violence, but there's good reason to hope it wouldn't be on the scale we see today.
The hand-wringing over Bitcoin's energy consumption, and suggestions of sacrificing decentralization for it, I'm not sure are justified just yet.
Electricity is very fungible, and hydro locations are limited. This means that when the (very limited) hydro energy is converted into heat to mine bits because it is easier to colocate some ASICs next to the dam than an aluminium smelter - then the smelter will run on slightly-pricier coal instead. The marginal carbon emissions can still be blamed on the coin mining.
Where we are right now is that the news aggregators aren't that good, and the interested communities are currency specific who will downvote censor any potentially negative discussion because of their investment.
Its very NIMBY
Due to this relative nature, I don't think that is valid reason to shut your mind off to discussion by trivializing other network's sizes.
Cryptocurrencies gets attacked all the time. Much smaller and more insecure cryptocurrencies are double-spent where possible, because these "bug bounties" are still worth several hundred thousand dollars.
Its not international news when it happens. It happens.
I think that in reality, PoW systems become more centralized over time. You can already see that with Bitcoin. Eventually the gatekeepers become those with the largest energy resources available to them, and "we the people" will be in the noise when it comes to hashing power.
I'd rather take energy efficient centralization than faux decentralization that also happens to destroy the environment.
It's not healthy for a society when people start self-censoring their actions like that. If nothing else, it places banks in a privileged position where they can get away with more predatory behavior, because people are more likely to see them as a necessity.
It's for this reason that anonymous transactions are valuable. You really should be able to buy legal marijuana or books about firearm construction without worrying that people might judge you. Neither is illegal, if you want one (or both) you should have the freedom to purchase them. However, many people would choose not to buy them, simply because they know the bank might see it on their balance sheet if they ever have to call the support line, and they're worried about follow-on consequences to their insurance premiums or their job if knowledge about that purchase ever circulates. That's a chilling effect in action.
On some stuff you cannot put a price tag - like mastercard ads say, some stuff is priceless.