So far the only people i know that successfully moved to
mexico had one of the following reasons:
1. They had legal issues/were part of the mob and wanted to lay low away from all the heat in their home countries. But even there their troubles back home eventually caught up to them in mexico as i've seen cases of expats getting shot at in Acapulco, Cancun, etc by the people they were trying to run away from. It's a temporary solution if you're trying to escape a bad situation, the ones still doing it change cities every few months or relocated somewhere in asia.
2. They enjoy corruption and found ways to benefit from it, since literally every part of the government there is for sale for the right price. Some found solid ways to do business in mexico and make profits without angering local criminals/affluent people.
3. They were in the tourism sector and their main business was in Cancun/Isla mujeres/etc.
Mexico is a good option for those who know exactly what they want. But if you move there as a tourist and expect paradise you'll be disappointed very quickly. It's not a place to "settle down and live a quiet life", at least not anymore.
If i was considering a move to a country like this, i'd probably pick the Philippines,
Thailand, etc. At least the criminal scene in those countries can be avoided to some extent if you got the money whereas the cartels are everywhere you go in Mexico.