It is true that no one can guarantee their victory even if they try, that is why no matter how good the talent is, there is no point in giving it if the victory does not come. In the field of betting, it is good to gain knowledge, but it is foolish to think of certain victory by applying it. No matter how knowledgeable a gambler is, he must rely on luck. Skill and experience can keep him a little ahead in winning but cannot give any certainty. Because there are many who have luck but due to lack of a little intelligence, they lose. Above all, I will also say the same thing that there is no such thing as talent in gambling that is innate. Success in gambling requires a combination of skill, experience and luck.
You are correct that there is no one who can guarantee their victory. If they could then they would be the richest man in the world. But I doubt there is any one who is on the highest 1000 richest man in the world. As there is no one on the top 1000 richest person I can say that there is no way to give guarantee about the winning.
It is mostly about luck or statistical probabilities. Strategies can help improve your probabilities from winning, but that is usually just slight shifting. No poker strategy can save you if you end up on a very unlucky streak of cards. Some people end up exceptionally lucky for a while, but this can be balanced out with negative streaks. Nobody in the richest people list made it from gambling, and there is a reason for that as we have just stated.