> Regarding Bitcoin [...] the network is increasingly moving [...] more efficient mining practices

Has Bitcoin changed its mining protocol?

It is and always will be Hashcash with SHA256d as hash function.

That's an example of sunk cost fallacy, where the miners have spent so much money on otherwise useless ASICs that they obstruct any attempts at progress.

That's not a sunk cost fallacy, that's just sunk cost.

> not necessarily decentralizing value hoarding (though it largely does that too)

I could have agreed with that if it had a fixed block subsidy. Not with the repeated halving that leaves each next generation with 32x less bitcoin to mine.

No, the second paragraph was correct. Bitcoin has been a complete failure at accomplishing any of those things you mentioned. They're all just wishful thinking by Satoshi and his fans, that never became reality. In practice it's not decentralized (the network is consolidated into just a few mining pools), it still requires central authorities to validate every transaction (the miners), it doesn't reduce points of failure (see any of the high profile collapses causing lots of people to lose their money) or censorship (historically disadvantaged groups largely aren't using cryptocurrency because it's overloaded with scams). The fixed supply is itself a man-made policy (it's not actually governed by math) and doesn't counteract inflation (see how often the bitcoin market has crashed). The use of renewable energy sources doesn't change that mining is a complete and total waste of energy (see any of the other coins that managed to ditch proof of work). Lightning network is also a complete failure of an experiment that solves nothing and only creates additional scaling problems (see here for a long list of problems, few of which have been addressed: https://github.com/davidshares/Lightning-Network). The number of open Lightning channels is actually shrinking because of how impractical it is to have your own channel (See also: https://bitcoinvisuals.com/lightning).

> It's designed to be a deflationary currency to counteract inflationary fiat systems,

Even if you take this conceit, we have to step back that bitcoin has irrevocably failed. Governments have definitely proved that they can regulate bitcoin transactions through various mechanisms. In China, mining is banned. In US, they are considered securities and regulated. No use case has emerged to truly transact in bitcoin. The only deflationary aspect is it's value in relation to fiat currency, which is still downstream to the supply of money controlled by central banks.

Personally, I don't think bitcoin is viable. The root of the problem is that no one is willing to transact in it. But beyond that, looking at it's implementation, I am not convinced that it accurately models the relationship between demand for the currency and the people willing to mine it. It seems very dogmatic to assume that it is just a logarithmic relationship between computing power and money supply. At the end of the day, there might not be a more efficient solution than some kind of political process.