When a new casino is about to decide the games to have on their platform do they consider the popular games in the specific regions where they intend to make their gambling services available, or selections are usually based on popularity of games generally?
It's not that simple.
Casinos need a game provider first, so you will first need to check with that provider how much the deal is worth then look at the legal point, and then look at what you face in terms of competition because it does;t matter if you provide a popular game in a market that is already saturated by bigger guys who manage to cut better deals and are already established and it might be more lucrative to bring in a new game that might be a success or a total flop in a few months but at least you will have something that is unique to your name.
Also, there is the thing about licensing, sports betting might be all the rage around you but when you start picking up bookie after bookie you will see none of them are actually licensed to offer that in your country and basically you will either have to deal with the issue of operating from an offshore company or simply skip on 90% of the sports you an offer to bet.
It's all a matter of laws and how much of a marketing budget you have on your back, with a few tens of millions you can make every game no matter how shitty and with a cursed RTP popular in a country by bombarding every social media with ads.