1. Support from the government.
Countries who gamble a lot has solid laws protecting their players so gamblers in those countries can just freely gamble as much as they want without having to worry about their rights. This doesn't mean that the countries have very free and loose rules but it just means that they have clear frameworks. Some other countries have some limitations but since their rules are clear, many still gamble.

2. Bigger paychecks.
Not all rich people are gamblers but they certainly have more chances to gamble if they wanted to. According to data, the higher the income is in some countries the more people gamble in that country. Since the average citizen is earning a lot, even if they spend quite a significant amount of money in gambling this will still not cause financial doom.

Is it fair to assume that a better economy and a solid framework will make people gamble more but be addicted less? This is the source, by the way.