Sasuke might be one of the main visitors. Their relationship has always been complex, and perhaps Sasuke is curious about Naruto's new venture. Shikamaru could also be a regular. He's smart and might be interested in the strategy involved in casino games. And then there's Kakashi. He seems like the type who would drop by now and then, just to keep an eye on Naruto and see how he's running things.
Mostly, Casino is not based on a real-life account. It's a creation of the writer's imagination, combined with elements that might draw inspiration from common themes and scenarios, but not from a specific true event.
The casino was a place full of excitement and risk. Neither the gambler nor the casino owner could predict their fate. Gambling can make people greedy, selfish and heartless. It can destroy a person's life and family, and even lead to social chaos and collapse.