The hosts, a superpower in the sport, had high hopes in all three races at a packed Gangneung Ice Arena but they endured an evening to forget as the short-track competition wrapped up.
The tone was set when Choi's bid for an Olympic treble ended in an unfortunate wipe-out with fellow South Korean Shim Suk-hee.
Choi, gold-medallist in the women's 1,500m and 3,000m relay, clipped the blades of Shim in the final lap of the 1,000m, sending both skaters hurtling into the side padding.
That left Suzanne Schulting of the Netherlands to claim gold, with Canada's Kim Boutin taking silver and Arianna Fontana of Italy the bronze.
Then in the men's 500m, South Korea had to settle for second and third in the shadow of China's Wu Dajing, who set a new world record.
The silver medallist from Sochi 2014 clocked the fastest eer time in his quarter-final, and lowered that with 39.584sec in the final.
South Korea's Hwang Dae-heon finished second, with his compatriot Lim Hyo-jun taking bronze.
In the men's 5,000m relay, South Korea were knocked out of contention halfway through the race after a fall left them three-quarters of a lap adrift.
Further ahead there was no stopping Hungary, who held off China with Canada taking bronze to claim their first Winter Olympics gold, and first medal of any colour since 1980.
Hungary -- Csaba Burjan, Victor Knoch, Shaoang Liu and his older brother, Sandor Liu Shaolin -- did it in style, setting a new Olympic record of 6min 34.510sec.
Choi had been regarded as a poster girl for the Olympics hosts, but the 19-year-old experienced a rollercoaster ride on home ice.
Her hopes of four golds were dashed from the start when she was disqualified from her opening 500m race.
Choi got off the mark when she won the 1,500m, and then led South Korea to 3,000m relay success.
But she only made Thursday's final through the back door, when a penalty to one of her rivals earned her a pass to the decider.
Starting on the outside she was always up against it, and she ended her race -- and her Olympics -- unceremoniously on her backside.
For Boutin, this was a step up the podium after filling bronze in the 500m and 1,500m. She received abuse from Korean trolls on social media over Choi's disqualification in the 500m.
Schulting was part of the Dutch relay team that set a new world record on Tuesday in the 'B' final on their way to bronze behind Korea and Italy.
Fontana, 27, added silver to the gold she won in the 500m and relay to swell her Olympic medal haul to eight.
Despite the disappointment for South Korea, they still had a respectable haul from the short track, with Lim Hyo-jun winning the men's 1,500m to go with Choi's two titles.