So #KLeague released some info on their income & expenditure for 2020, and in there was the revenue from broadcasting rights - 6.8 billion KRW. But the no. 1 source of income was "체육진흥투표권" - translates literally as "Sports Promotion Voting Rights" - at 10.2 billion KRW
Searching about this, it's all linked into "toto" (e.g. SportsToto, KToto) - the Korean sports betting business. It's not like UK betting, it's more like a national lottery/Lotto in that all proceeds go into a national sports development fund
KSPO issues toto licenses and the Ministry of Culture/sports/tourism oversees it all. The SportsToto website has an English version if you're interested:
https://www.sportstoto.co.kr/global/sports_betting.php?lang=en
This may be common knowledge, but I'd only heard of SportsToto in relation to a WK League team before
https://www.sportstoto.co.kr/global/sports_betting.php?lang=en
This may be common knowledge, but I'd only heard of SportsToto in relation to a WK League team before