Something that wasn't mentioned yet is that the exchanges need to support your local currency if you plan to withdraw or deposit into the exchange. For example, Coinbase has a breakdown of the countries that is supports and what is possible for those currencies:
https://www.coinbase.com/globalIf you want to transact in let's say Mexico Pesos, then you are limited by a much smaller subset of exchanges that can be used. While most of the major FIAT currencies are supported, there is a huge demographic that most crypto exchanges haven't supported yet.