Even by the standards of Korean politics this was the most bizarre thing I've ever seen.
The President declares martial law for basically no reason other than "the opposition party keeps opposing me".
He then tries to impose it with just a few hundred special forces soldiers—most of whom hate him(Yoon has like 10% approval rating among males aged 18-40)—who were understandably very unmotivated and didn't really try to stop legislators from entering the National Assembly building, and meekly lifts martial law a few hours later when the assembly votes against it.
It's such a unimaginably dumb move that nobody can think of a explanation other than that he was drunk.
Yeah he was a unpopular, lame-duck president but he had two and a half years to go. He could have spent that time traveling around the world, play golf with Trump or whatever and then retire comfortably.
Instead, he decimated his own party, even attempting to arrest the party leader, and completely self-sabotaged his government, leading to his entire cabinet's resignation. This will likely usher in Lee Jae-myung—the opposition party leader and one of the most radically leftist politicians in Korea—as the next president, who will ensure both Yoon and his wife are jailed for life once his term ends, whether naturally or by impeachment.
Yeah Korea is insane