So people need to understand that a game that you play to win some reward and lose nothing if you don't win can't be and shouldn't be considered gambling but it is just a game that you play for some reward, even if it involves making predictions on real life events like sports matches, etc.
Different opinions about considering gambling without a stake. That can be true in some forms because you've got nothing to gamble with. But we can't also deny that winning and losing is part of gambling and that's why we do something and you're expecting to win, the risk is already there. And it's up to you whether to consider it as gambling or not when you're not putting a lot of pressure and risk on what you do. Considering that we also play gambling and we also could have some reward if ever we hit our bets and we're lucky enough. So, that's it, you do you in considering topics like this.