Well, nothing is so surprising about the USA leading gambling in every category. As we can all see, sportsbook, odds, spreads, and other sports betting related terms are what the sports casters talks about every single game. Even the commercials, casinos are always present. They are even a huge sponsors in mini games happening during timeouts and halftime.
However, I was expecting some countries in Europe would dominate the top 5. Looks like they're the kind of luxurious gamblers or maybe I'm just stereotyping here lol.
I was also surprised that there is not a single European country, but probably it depends on the mentality of the inhabitants, the prevalence of advertising gambling, the fashion is easy to get rich among the population, the cult of money, wealth and many other factors. In my country, I notice more and more advertising gambling and I think that the population is actively and is more and more starting to play. I understand a lot in the psychology of players and the mechanism of the very game, the emergence of greed and the desire to recoup, but ordinary players do not have such experience, especially for beginners.