How religious the country is will also determine their gambling habits. It doesn't matter how wealthy the people over there are or how vibrant their economy is, if the country has more religious population their gambling activities will be extremely low compared with countries that doesn't care much about religion. So this should also be put into consideration when deciding why some countries gambles more than others.
Religion can be a big factor affecting the mindset of the people and influencing them not to gamble. But I see that money (income) is one reason why a rich country gambles more than a poor country. This is not just talking about the population but also the capacity of the individuals to spend on gambling. They don't gamble as they chase to win but just to enjoy their life. It was a different story from those who live in poor countries, where they choose to risk and gamble for the sake of money.