A charismatic jeweler (Adam Sandler) makes a high-stakes bet, but in this high-wire act, he must balance business, family and adversaries on all sides in pursuit of the ultimate win. Also starring Kevin Garnett, Julia Fox, Idina Menzel and Mike Francesa. Rated R. In theaters Dec. 25.

Kevin Garnett said on Tuesday that he was not surprised Kyrie Irving left the Celtics for the Nets this past offseason.

“No,” said Garnett, who won a championship with the Celtics and later played two seasons with the Nets. “Boston’s a tough town, dawg . . . You’ve got to want that. The people want it for you. That’s why Paul [Pierce] was perfect for it. Paul wants the shot every time.”

Garnett was speaking at a roundtable with a dozen sports reporters alongside Adam Sandler and the directing brothers Josh and Ben Safdie to promote their film, “Uncut Gems,” which opens on Dec. 13. Garnett plays himself in the film, which is generating Oscar buzz for Sandler’s performance.

Sandler and the Safdie brothers are avid Knicks fans. Garnett is not, but he knows a bit more about basketball than the other three do, and he said he thought that Irving and Kevin Durant should have chosen the Knicks, not the Nets, in free agency.

“If they did the Nets, I thought they should have done the Knicks, if I’m being honest.” Garnett said. “I’m not a Knicks fan by far. But if they come to the city and dominate, man, the first superstar to hit New York and be vibing is going to be bigger than life. Remember I said that. Any piece of hope in this city is going to [soar]. People are waiting.”

At least the two would have had each other in Manhattan, once Durant is healthy. Garnett said he would not have signed with a team such as the Knicks — or any other team — without help.

“You got to come with pieces,” he said. “I don’t think [the Knicks] put superstars around Melo [Carmelo Anthony]. They had, obviously, the pocketbook to be able to bring players here. But for some reason, they haven’t just put it together.”

Nets forward Kevin Garnett shoots past Magic forward/center Glen Davis at...

Nets forward Kevin Garnett shoots past Magic forward/center Glen Davis at Barclays Center on Jan. 21, 2014. Credit: KATHLEEN MALONE-VAN DYKE/Kathleen Malone-Van Dyke

Why haven’t the Knicks been able to win consistently for two decades?

“I don’t know, man,” Garnett said. “I wish I knew so I could go up there and say, ‘Hey look, I got the plan.’ But pretty much anybody looking at [former team President] Phil Jackson, like, ‘[Expletive], I could’ve pretty much done what he did.’”