Probably a small number of people can boast of being able to walk away from a casino with a winnings, and there are many more stories of failure. Risking your last remaining money is not a smart thing to do. I don't think such people have any strategy or plan of action for sure. It's just a huge success that happens very rarely, maybe even once in a lifetime.
True, it doesn't usually happen. It is totally on luck. However, it is not unusual to win small amounts of money here. As happened to Smith. But he gambled with $5,000 for about a week and won $17,000. This amount is not very high in gambling where many people have records of winning millions of dollars with keeping very few dollars.
Those who earned million by just using few dollars are very rare for sure and they are very skilled because of how the result of their gamble turned out. For me winning 100x from the starting capital is big enough and I can consider it as a big win but doing 10000x from your current amount is outrageous and I'm imagining to be nerve racking because it can turn out to be a disappointment if bad things happened. It certainly need good amount of luck, skills and experience to achieve those kind of winnings.