probability only really means something if you intend to do something a number of times. In trading, time only happens once. With that said magnitude is more important than probability.
In trading the only thing that matters is your outcome. You may never get the chance to try a number of times in order for the probabilities to work in your favor. (Magnitude /Consequences should be measured with probabilities).
For example the chances of winning the lottery are very low. But if you win who cares if the chances of winning the lottery again are almost impossible.
In basketball they have free throw percentage. In reality the player has two outcomes, miss the shot or make the shot. So what does 60% free percentage mean?
If it's during the season it is helpful cause the player is going to take free throws throughout the season.
But if its at the end of an important game and making the free throws is the difference between winning the game and losing (magnitude) then probability means nothing. The only thing that matters is the outcome.