Almost everywhere there needs to be a on AND off ramp, or only the most diehard hobbiest or desperate economic actor will consider it. This stuff is just too new, and there is too small an ecosystem for all but a small handful of coins for them to actually act as a useful exchange medium.
Local currency does still get used, it’s unavoidable, and causes losses. There is no perfect solution.
One economy which fits the description is India - check out the boxes of cash hah! [https://www.livemint.com/Politics/eGzzHAcOe5VePoyCd7n0EN/Inc...], and [https://timesofindia.indiatimes.com/city/mumbai/mumbai-raid-...].
(FYI, a cr or crore == 10 million, a lakh == 100k. Even at current exchange rates, that is a lot of money anywhere, and an absolutely massive fortune in India).
But there is an element of this in ALL economies, including the US. It’s a matter of scale/ratios, not a yes/no thing.