When something is determined by luck, then strategy won't work because luck determines everything. What strategy will we employ to win the next round of slots? I don't think there's anything we can do.
Many people claim strategies, tips, and tricks for winning, but in reality, they lose more often. Perhaps they were lucky when they used a particular strategy, but they attribute it all to strategy. I don't blame them, nor will I condemn their beliefs, but I personally don't believe it's feasible.
It probably depends on the type of gambling, too. I don't think all types of gambling require a strategy to win. Some rely purely on luck without any skill or strategy, while others do require skill or strategy to win or increase your chances of winning.
I think people who believe they have a winning strategy are simply relying on luck. They use their strategy, and luck happens to be on their side, resulting in a win. They conclude that their strategy is indeed successful, and even if they try it again in the next round, it won't necessarily result in a win, right?