It's easy to use cryptocurrency as currency, but how many country is legally accepting Bitcoin as currency? only in El Salvador, the rest country are either grey area or only accept it as commodity, although there are few businesses don't mind to accept Bitcoin as alternative payment.
Bitcoin is just a "currency" similar to fiat, if a poor can earn $100 per month and get paid in fiat, it means there's no change if they get paid in Bitcoin. They still get paid for $100 per month, in a different "form".
You can use Bitcoin everywhere if you have Internet and a device to connect it to Internet and broadcast your Bitcoin transactions.
You don't need Bitcoin to be legal or more as legal tender to use it. Using Bitcoin in nation where Bitcoin is legal or legal tender is safer than in country where Bitcoin is Alegal or Illegal but even so you can use it in those countries with different restriction against Bitcoin.
There are two countries where Bitcoin is legal tender: El Salvador and Central African Republic.
https://coin.dance/poli/legalityhttps://coinmarketcap.com/legal-tender-countries/