As long as there's a risk involved and it is some kind of prediction, win or lose type of games, then I would always consider it as a form of gambling.
Sometimes even if it's not directly money as long as it have a value and it is being risk then yes it is gambling.
Sometimes we forget that it is gambling and still think it is not gambling. We think that anything that uses money is gambling, whereas that does not use money, it is not gambling so in predicting it, we say it is not gambling. But as you said, whatever it is, if there is value to be gained from predictions, it is gambling. Well, that is the response from people only.
Actually the response to this Op case is still a hot topic of conversation because everyone has different opinions and thoughts, like now you think it's gambling because there are several risk triggers to gamble using real money.
For myself, betting for free to get real prizes from the results of this prediction can be considered open gambling as long as we consider this only a game that allows us to earn money from this guessing or prediction game.
But it will be gambling if the person is triggered by this prediction and bets using personal money to predict, then this is gambling.
So all responses return to their respective mindsets.