The mighty have plunged deep into the depths of despair in this woebegone sequel to “Bad Santa.”

One of the smartest and funniest Christmas satires, the 2003 picture relentlessly savaged the commercialism of the season and retained a smidge of kindheartedness, with Billy Bob Thornton in what might go down as his signature role. It’s given way to an outdated sequel that has little to offer but an endless stream of insults.

The picture plays like the cinematic version of a low-rent comedy club, where the only practical bit is for Thornton’s Willie Soke, his partner-in-crime/double crossing pal Marcus Skidmore (Tony Cox) and his hard-edged mom Sunny (Kathy Bates) to hurl playground-insult level invective at each other.

There’s barely an attempt made at crafting a plot — Willie, Marcus and Sunny endeavor to rip off a Chicago children’s charity run by Christina Hendricks — and the spectacle of a hard-living, inebriated, sex-addicted Santa simply doesn’t have the same comic juice the second time around.

Thornton, Cox and Bates are wonderful, of course, and if there’s anyone who can salvage some level of dignity amid the third-rate vulgarity, it’s them.

But then there’s poor Brett Kelly, whose lonely, poignant Thurman Merman softened the first movie’s edge, and is here reduced to playing Thurman as, well, the exact same person, without any adjustment made for the 13 intervening years. What was once charmingly weird now plays as creepy, mirroring the movie itself.