Completely agree with you!
The World Cup or even the football championship on some continent is not interesting enough. I like club competitions of professional teams much more. It is more interesting to bet on them. And also you always have a club for which you always worry and are its fan. But of course, such bets are not always possible in large international casinos.
But, I think with the development of the gambling industry, this will also be common at the regional levels of competitions and football and cricket, tennis and other competitions for which bets are possible in large casinos.
True, our interest in this football club team has more options. But it's doesn't mean the national team has a small support base for gambling. Precisely for the national football team, the number of fans is much larger. That means each match will have a greater betting potential as well. Even those who don't like football will also bet when the world cup running.
Perhaps we have different opinion, but I think local competition such as EPL, Serie-A, or Champions League has bigger number of fans because it is not limited to where we do live.
For example a team like Real Madrid, their fans base are all over the world from many different countries but if we talk about National Team then it is limited to their own country.
In case of potential betting, I have no valid statistic about how much is the average betting amount placed during World Cup compared to Local Competition/Leagues.
But for sure every competition has its own market and perhaps World Cup has a big market because this event is not happening every year.
Yes, every one of us has our own favorite sports and athletes. FIFA World Cup is the biggest sporting event together with the Summer Olympics. Even if my country cannot qualify for a World Cup, I am still interested. But maybe the European Champions League is more exciting since we can watch superstar tandems in many clubs that are competing against each other. We can only count a few teams that are competing in the top for EPL and Serie. But my favorite sports and leagues are boxing, NBA, UFC, and DOTA 2 in e-sports.