Any gambler that makes a prediction without internally associating it with a probability is one that's most likely losing money. You simply cannot consistently make positive-EV bets without considering the probabilities of your predictions. (Heck, EV is the linear combination of probability and payoff.)
A scientific model almost always includes a very specific kind of probability: the p value. The best scientific models are also validated externally and have the results of that experiment reported -- as probabilities: false positive and false negative rates are common concepts to discuss that.
I completely agree that one can predict something that one does not believe to be the most likely outcome. But in order to even say that, you have to be implying that there is at least a partial order from "least likely" to "most likely" and that order is commonly referred to as probability.
(Edit: oh, I see where you got the "most likely" from. By convention, in a binary prediction, the prediction itself is stated in terms of the most likely outcome, with a confidence between 50 % and 100 %. It is of course possible to state the other side of the event with a confidence level < 50 % -- it's just not the way these things are usually presented.)
