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?
Betting on the the potential loser comes with higher odds and bigger profit. So it will not bad place bets on the dark horse since it will bring more returns. Betting on only favourites might never bring a big won. Hence, it will not be bad advice to consider following the higher odds and bet on underdogs sometimes.
Nevertheless, I will never get bored with winning. So if betting on favourites gives me consistent wins, I don't think I will ever be bored. Gambling is more entertaining when you win.