The Reason the Climax Doesn't Work

It's because Walken's character is an bottomless pit of money. The stakes are set up that Callahan's character might lose and, if he does, he loses BIG TIME, but then a few minutes later Walken informs everybody that the amount of cash in play is huge to the hustlers and gangsters, but to him it's barely different than the pocket lint from his suit. Without the intensity of the high-stakes at the end, the showdown is meaningless. They set it up so the climax is about win-or-lose but there is no lose.

But there's a deeper issue throughout the film, not limited to the climax. The end would play differently, of course, if Callahan's character was going through a better personal arc, but that stuff was underplayed compared to the physical threat of Palminteri's character. The focus should have been on the main character's arc as a player and as a person, and the story would derive its drama from that. As it stands, the main character isn't going in to prove anything or fighting some inner demons, he's just going in to win. Then, because of Walken being the biggest pocketbook in the room, he can't do anything but win.

The movie is fun, but it's fluff, and that's why.