It really seems like a race to the bottom. We produce specialized hardware, stick 'em in giant mining farms where they devour power - for what? Crunching arbitrary numbers. It just seems incredibly wasteful.
Bitcoin advocates ought to understand that the whole mining thing, and the increase on the rate of difficulty in mining, and the eventual limit on the number of bitcoins that can exist, are just as artificial as anything that happens with fiat currency, and controlled by a much smaller number of unaccountable people.
Except that fiat money is stored on a "normal" server.
Not on many computers that constantly do full power calculations, on purpose!
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 correct that the cap on Bitcoin is somewhat arbitrary, but the point is that there IS a cap, which is not the case with fiat currencies which can be printed indefinitely (which is why the purchasing power of all fiat currencies goes down over time).
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!
Compared to the military and law enforcement which back a regular currency, it's incredibly efficient. Especially when you count the human cost of conventional power politics in terms of oppressed minorities and corruption.
We had military and law enforcement long before regular currencies. Societies were already investing significant amount of energies into these activities as well.
The idea that switching to bitcoin or whatever will remove the need for either is a bit far-fetched.
The advent of currency took them to a whole new level, though. Graeber describes the new social structures around currency as a "military-coinage-slavery" complex in his book Debt.
War was prevalent in primitive societies as well, it hardly appeared with currency. Currency and in a more general way, an organized society makes you better at waging war, hence their success. If anything primitive societies' wars were bloodier compared to the population base.
As for crime and law enforcement, it's the same, people have killed for some gold or cows since eons.
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.
As the link I gave in the GP argues, currency was specifically developed as a tool for population control: As the sole source of currency, a state can influence its people's priorities and behaviors by providing a budget for the tasks it wants accomplished. All tax must be paid in the state currency, which creates an intrinsic demand for it from the whole population, and ultimately the only way to obtain it is to fulfil the missions on the state budget. Hitler's Beneficiaries: Plunder, Racial War, and the Nazi Welfare State [0] provides a very good overview of how this worked in Nazi-occupied territories, but it's a similar game in any nation state, autonomous or otherwise.
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.