As Venezuela has become dollarized, inflation has come down. Even their idiot president Maduro admits the dollarization (which was done by citizens spontaneously ignoring their govt's ban on dollars) is a good thing.
A year ago, some of us were hoping that Venezuelans would have adopted bitcoin as their currency (or an alt). But the rolling electricity blackouts not only mean you can't use credit cards, but you can't use cryptocurrency. So they've gone with old fashioned US dollars in cash.
This whole real life case study shows that cryptocurrency won't get adopted in poor countries (because of lack of electricty). It will get adopted in rich countries - rich regulated countries.
I still have high hopes for the more stable African countries that are already accustomed to mobile payments. These countries usually have enough electricity to run their phones but majority of the population is still unbanked. That's one niche cryptos can still fit in if it cannot completely replace the existing mobile system.