As wiki says the current king took part in the last one (he wasn't a king yet back then). And he is very proud of it - all participants get a pin (elfstedenkruisje) and he wears it next to the other "medals" he has even for official occasions
https://www.omropfryslan.nl/nieuws/248240-koning-draagt-elfs...
EDIT: just to add: I'm not a royal bootlicker. I just think it's one of a funny wacky things he does. Like participating in the "throw the toilet" competition