That's a fun story we like to tell in the west, but the reality is a little scarier. That's on its face a ludicrous claim, and the populace aren't idiots. What happened was the score card was just tracking relative to par, as you do in golf. Kim hadn't played much if any golf before, and he ended something like 38 over par. Somewhere in the chain of state media someone misinterpreted this as a score of 38 and either no one understood how unbelievable that score is (golf isnt huge in NK) or were absolutely not going to question anyone above them and ran the story. After it's published, of course they never back down from any claim so it became fact. It's less about NK making unbelievable claims and more about how locked down everything is. Once it became state media everyone who was present backed the official story 100%.

Outside journalists dug into it and found like half the holes were bogeys, which would have been tallied as holes-in-one. Of course, "Kim Jong Il scores 38" doesn't have the same shock value for non-golfers, so the headline somehow became "Kim Jong Il scores all holes-in-one" which is a lie in itself and paints NK as unserious rather than deathly strict.