Are there counterexamples in the real world? For instance, has the British Pound been subject to hyperinflation? Has it been reset?
You actually chose one fiat currency that managed to survive the longest. There's only a few of them and there's something they have in common, which is being world reserve currencies.
This ups their demand and boosts confidence, thus saving them from high inflation and a possible reset, but... recently we saw an all time low of GBP to USD. Maybe it's a beginning of something.
What incentivizes spending Bitcoin? It doesn't decay if you don't use it. Doesn't it incentivize saving/storing it as an investment for future yield?
Maybe that's what businesses should be doing. Incentivizing you to spend your bitcoin by offering bitcoin users something more and better, something that can't be bought with fiat money, the exclusivity that you've mentioned.
Having bitcoin as an alternative for hard times is also a great idea because it cannot be taken from you at an airport or in times of war. The recent situation in Ukraine can be a good example.
Russian soldiers were looting homes and robbing fleeing Ukrainians. Hiding jewelry or diamonds might work in this situation but moving large amount of cash, or gold is impossible.
If you get your wallet stolen while traveling abroad it's usually a big problem but bitcoin can come in handy if you have a way to access it.
These are interesting use cases, especially the latter - which is more of a social construct based on exclusivity.
The second part is possible in jurisdictions like El Salvador where they've made Bitcoin legal tender and might have such an incentive.
The first part has been demonstrated before.
A caveat: I used to help e-commerce businesses transact with Bitcoin but the transaction fees made that untenable. Yes, we have solutions like Lightning today, but that only means that Bitcoin's original vision as having low-fee transactional utility isn't feasible. Unless that wasn't ever Satoshi's vision (but it sure seemed like it, given he also believed mining would be more democratic "across laptops" and hadn't anticipated mining pools yet).
Were the businesses trying to sell cheap products with a lot of transactions per day? Probably also at the wrong time when we had "hash wars". 2017-19 was probably the worst time to be integrating payments because the fees were skyrocketing due to all that drama with BCH and BSV. Now it's much better. You can have a transaction processed for $2.
This won't work at a coffee shop of course, but should be competitive form of payment at restaurants or gas stations and beats the bank when it comes to more expensive stuff like domains and accounts, electronics, luxury goods...
A caveat: those who buy Bitcoin before each major price movement may feel cheated when their "spending" looks foolish in hindsight, and they should've "held on" which, over time, leads to less spending and more hoarding.
They buy, there's a move up, they feel cheated, but if they spend and there's a move down, they feel good. Just like someone who buys a washing machine to see it on 50% sale the next day. You can never make everyone happy. Some will always feel like they could've done better. I expect big price movements will stop at some point. Bitcoin isn't mature enough but you can see it happening right before our eyes. Bitcoin used to go up 20x and then lose 90% of its price with daily swings of 50%.
I think the evidence is in front of us that it does work as a deflationary currency, alongside other inflationary currencies.
A caveat: just not the way it was possibly intended? How firm was Satoshi on Bitcoin as having low-fee transactional utility vs. being digital-gold-store-of-value? I've read a lot of his emails and work but it always felt like he was adapting to the changing climate as mining hashrate spiraled out of control. Happy to have contrary sources - or, a clear timeline of what "his vision" was and if/how it changed.
I'd like to know what he thinks about it now and how would he like us to adjust. He wanted the community to shape it and make it work the way we wanted, which is why he left it to run its course.
We can only guess that his goal was for his experiment to be a success and whether it was used more as a currency or a store of value was less important.