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?
Why wouldn't i? Isn't the whole point excitement and decent odds? I am pretty sure that huge portion of us don't always bet the one with lowest odds, or the one majority's favorite.
It would be pretty boring just to bets the front runner on betting odds. I know because i tried this and imho it's counter productive as well, because those odds often won't add up enough to cover the costs in the long run. So why wouldn't i add a random black horse from time to time. In fact those situations are the times i have made most money. Not that i wouldn't be on negative still when it comes to overall betting.