Being a croupier seems similar to working the pig smasher machine in a slaughterhouse. But I wouldn't want to watch a cool pseudo-noir descent-into-madness SCANNER DARKLY-ass film about the latter.
Ebert wrote that plot was besides the point for this film, in favor of deep characterization and atmosphere, but that's only the case for the first 2/3. For no good reason, the last 1/3 crams in more plot than the story can hold. There are like four twists in a row, none of which are earned, and all of which feel like the result of studio execs complaining that the first cut didn't have enough going on. Would've been a 5-star weird gambling-themed NIGHTCRAWLER-antecedent if it'd stuck to its best formulation.
In any case, I would not be friends with Jack, because he is a menace and rude to his girlfriend.