While this is definitely somewhat generalizing, I think there is some merit to it.
As poker is a game that is easy to play but hard to master, one could argue that only the most determined and intelligent people will rise to the top, therefore countries with a lower average IQ should also perform worse on average (ofc this is only true if the same percentage of all iq groups of every country would participate evenly in these games, which I'm sure they're not).
If you take a look at average IQ distribution maps by countries, f.e. African countries and some of the south-american countries are on the lower spectrum on average (70-90 iq on avg), same applies for some of the UAE countries.
So if I had to take a guess I'd say that these countries probably have the most fish playing, while playing people from the UAE should overall be the most profitable (as they seem to be on the lower IQ spectrum + have lots of cash in their economies)
Just my 2 cents ;D