People definitely always get the idea before elections that which party is going to win the game.
A very biased thing to say. How on earth can you possibly know which party will win when both of them have equal chances of winning? Not every country is corrupted and you may support one team does not necessarily mean that team will win.
But there is a huge lot of people who still are not aware of the games played by political party and if they bet on politics, may be they can give gambling some profit.
Yes, the bookies will be earning a good amount. Its like throwing stones in the dark and not similar to just any other EV+ game like sports betting where you have to do some research. So bookies have somewhat an advantage here.
But as you said, people do not find betting on politics interesting.
Looking at the number of bets on sports betting sites that the Trump VS Hillary poll was, I would say they are very interested.