And you are right, imo, because gambling, by definition, is about staking something valuable. Yes, some activities, when nothing valuable is at stake, still called "gambling" sometimes, but those cases are the topic of discussion rather on linguistic forums than here in Gambling section.
The reason why many people choose to gambler is to make more valuable profits from what they do. You put your money so that you can make more money which is simple. If you don't bet we'll or have to amounts of luck for you to make a winning, then you are going to lose money totally without getting it back. You win other lose, if other win, you lose. Simple pattern how gambling works.
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If by "other" you are referring to another human gambler, then you need to know that the concept of you winning and others losing only comes when there is a multiplayer game being played and you are not against the house only, because in most gambling games, you are up against the house and in that case, it is only you who either win or lose and mostly you lose because of the house edge.
Luck is obviously the only element that you need in gambling to succeed, otherwise, no matter how much money you carry with you when entering a casino, you will come out empty handed if you don't have luck on your side.