In most under-developed countries, where there are few employment opportunities, people tend to try gambling to change their faith. That's one reason why gambling is increasing all over the world.
I don't think gambling is popular in under developed county. When people have money they can try options but when they don't have much to live then their options are limited. I guess westerners are the targeted customers for gambling industry.
Yeah, they don't want to use the money for just gamble because they must buy their needs. Although the gambling itself is not popular in the under-develop country, I think some people still playing gambling because they believe that they can earn money with fast. People will play in the hidden place, and they will play the traditional gambling only because this is what they did.
Generally, rich people are the ones that gambles a lot. Some poor people gamble too but with limited volume and are mostly betting with their friends and locals. Some countries like Singapore imposed high entrance fees on their local citizens when entering casinos.