Lol comparing cryptocurrency with pokémon card is new level of... uh creative but not very bright perspective.
OK let us pretend Pokécard has some crypographically proven properties that makes it useful as currency.
Pokecard as a coin is speculative only when compared with fiat; one coin is one coin and its value stays in term of its utilities.
Regardless, further reading is usually very useful before forming strong opinion.
(1) I would argue speculative assets is a concrete use case which is a pros, it's for capital gain. Anyway, your speculative-as'a cons argument crumbles as soon as stablecoin is mentioned. Stablecoin is pegged to stable fiat.
(2) Deflation and inflation mechanism of cryptocurrency varies differently on each coin. BTC itself inflationary by nature due to its halving mechanism. Other coins may have same or diffrent approach.
By now I hope you would see the benefit of forming informed opinion: there are a lot types of Pokécard—I mean cryptocurrencies, reading few sentence about BTC does not mean it encompasses all cryptocurrency . ;)
Finally, since you are so obsessed with cryptocurrency as a way to subvert govt: it's only one of use case.
Stellar or Cardano (I forget) aims to be backbone for scalable, and cheap payment network, Ethereum is not only a currency, it has smart contract that allows you execute your program. Those has zero thing to do with a working govt or not.
Cryptocurrency, being a currency has its value tied to its utility (e.g. the usual talk about decentralized, private, and resiliency against inflation which have been beaten to death).
This is clearly an existing use for normal people. Whether it will gain wider adoption for everyday payment remains to be seen.
More importantly, it doesn't need the civilization to collapse. In fact if civilization were to collapse ain't nobody gonna validate your transaction!
The main problem is the malware that makes you lost access to your data.
(Pseudo-)anonymous payment (BTC is not fully anonymous) that facilitates the payment is just a side effect.
Backup and threat management directly address the main problem. Banning crypto just like you say, deter the payout potential, but it leaves the malware as is.
It's pretty funny when we talk ransomware payment in term of friction—as if we are talking about new payment method user which user will be inconvenienced.
Criminals doing criminal transaction don't care about 'friction', they will grind through any obstacle to move the money.
It's a "product lifecycle management" that is basically version control plus issues list tracker. It has horrendous 80-90s-era interface and require clicking for every possible steps. Formatting always involves MS Word style rich-text button with sans-serif font.
Worst: it has to stay Online just to do version control.
The remaining 25% hide under the disguise of generic security "concern" that usually involves tangential topic.
Case in point:
A: WebUSB has privacy risk, it can fingerprint you.
B: But it already require user consent.
C: ProcesD to pontificate about good user consent UX.