Crypto can be helpful for poor countries if it is widely accepted with the approval of governments and central banks. Moreover, it is not entirely true that crypto will be helpful for a country because a country must buy crypto and must store it for the long term. When the crypto market turns into a bear market, we have to think about what will happen to poor countries. It's not enough to just look at the profits of crypto, you must also keep the loss in mind.
That's about managing risks.
Surely, such countries wouldn't buy as much BTC they would make the situation in their country even worse due to the dip or the correction

To be fair, the poor nations that really need investing into bitcoin can't afford to invest into bitcoin because they are poor. Same as people, there are tons of rich people who are buying bitcoin, and getting richer thanks to it, whereas poor people can't afford to buy that much, so they are not getting as rich.
USA could get 100k bitcoins tomorrow, without blinking an eye, they could do that with what DOGE saved them so far. But in the end, El Salvador couldn't even buy a billion dollars worth if I remember correctly, not all at once, so it's clear that the ones who need the most, can't get it. But making it legal tender, and allowing crypto companies to cherish there, would allow them to get a lot better.