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.
This is the
source, by the way.
The source you have listed actually contradicts this
China (Macau) $1,354
Czech gamblers bet $76.80 yearly
The Czech Republic has a GDP per capita 3 times that of China and is gambling 20 times less, so this is a 60x difference in the opposite way.
Income determines how much the CAN gamble, not how much they will.
Besides, the thing is pretty obvious with Dutch people spending 4 times as much as Germans.
Also, studies say that close to 1/3 of the population of Nigeria has gambled at least once a year, compare that to the Czech Republic, where only 25% have. I don't think we need to compare the average wage, do we?