Everyone except bitcoin bagholders can see that the BTC proof-of-work protocol is obscenely wasteful. There are already superior cryptocurrencies that use different consensus algorithms and have similar or better security/anonymity properties.
Look the actual problem as solved by BTC which is digital cash with no protections like chargebacks requires only one single trusted entity (can be more if we want) maintaining a very simple ledger of transactions operating in the open with auditing done by interested parties.
This is plenty achievable given that banking, which is far more complicated and messy, works. It doesn't not require a small country's energy usage to achieve human consensus.
BTC is super cool having created an pseudoanonymous digital voting system that's resistant to ballot stuffing but we're allowed to make stronger assumptions for our financial systems.
I think the banking regulator and or justice system in the relevant country step in. Being in a modern society with laws seems to be the main, partly effective preventative measure. If we're going through the work to have laws and courts and regulatory bodies anyway, and if we have the FDIC etc, why shouldn't we get a partly-trustworthy financial system out of it? I mean, of course, not that the people are trustworthy, but that records of what you deposited, withdrew, transferred etc will be respected.
Even if you own crypto, I'm guessing you have a bunch of money in other assets in accounts managed by financial institutions. How often has the bank just decided that you don't own that?
