:://:::
It can be called bad luck if it is an affliction for him (one example is using money that he cannot lose), but if there is no impact of the affliction he received you can use the phrase “unlucky”.
The meaning of the sentence may be many definitions that can be described, but if he did not get excessive suffering or sadness from the bet made then I agree that the phrase “unlucky' for not winning the prediction contest is more appropriate.
I understand your colloquial language, but it doesn't change at all the reality of question of jargon in the game. Luck is directly linked to variance, which in itself has positive or negative values. Therefore, in popular jargon it is called bad luck, or good luck, etc (unlucky), in fact, even lack of luck does not exist, well, yes, but of course in the colloquial misunderstanding. The ideas that surround you are not always the reality of things.
And in this specific case it is not a point of view, as someone might surely think, since it is a measurable and quantifiable situation. In any case, to make you understand the definitions (slang): that you call "unlucky” or lack of luck would be something more similar to Breakeven.
