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Luck is not the biggest strategy in gambling, have been into gambling but not yet addicted to gambling, there is 20% of luck in gambling while others are specifically based on strategies. My own strategy is learning from the experts who have been; on the game over time to make a move as such as them.
Just keep in mind that gamblers frequently lie about their "achievements". You may think about them as of experts, while they are actually not. They just enjoy being mentors to others. If that's what you heard from those people, that " there is [only] 20% of luck in gambling", it's already alarming. You can improve your winning chances in games that are not purely based on luck, such as poker and sports betting, but luck still is the main factor. And if "the experts" are telling you that there can be a winning strategy for dice, slots or roulette, just ignore them and move on because most likely they are just sick addicted gamblers looking for attention.