In sports, there is always someone winning dominantly. It can get to a point where they are almost always expected to win. By that point do you continue to bet on those favorites to keep winning or does it bore you? Would you enjoy stirring it up a bit just for the fun of it and betting on the underdogs even if the chances are quite low?
That's why I like sports betting. Generally, a top team ends up winning the vast majority of matches. We only have to look at last season and see on average how much they won and lost. I am fully convinced that most of the time we lose it is because we want to win more, with mixed bets or betting on many matches with the intention of maximizing our own profits.
I don't think people get bored, it's just that if they change their strategy it's with the intention of making more money.