Out of KPop's major companies still extant, only SM, YG and whatever company Kwangsoo has now (his company changed names too often to track ) are original outfits.
F&C was founded by a minion of Kwangsoo, as well as Fantagio.
And JYP began as a house project of SIdus, a major entertainment management company in Korea back then. (Sidus, now called iHQ, mostly manages actors)
4 of god members belonged to Sidus, and only Kim Taewoo was part of JYP, whose company was to MANAGE god's activities. Later, when Sidus ended its singer project, 3 of the 4 joined JYP but Yoon Gyesang never did and went his own way, rejoining god much later so YGS was never part of JYP.
JYP did run Park Jiyoon and some others whose names are forgotten now, and in 2001 what we now call JYP Entertainment was formally born. Hong Seungsung, who founded Cube Entertainment (he no longer owns it btw) was named its president, and Bang Sihyuk, one of JYP's composers, was also named as co-founder.
Big Hit was born as an in house project of JYP. How much of Big Hit JYP initially owned is unclear, but Big Hit began as a sub-label of JYPE, with Bang Sihyuk having exclusive control over Big Hit (where he ran the act Ei8ht, out of which Lee Hyun still remains with Hybe) but at the beginning Big Hit was little more than a subsidiary of JYPE.
JYP went to USA with Wonder Girls, and in his absence he branched off some of his artists to Cube, and 2AM to Big Hit. 2AM won a Grand Prize while Bang was managing it, which became Hybe's first Grand Prize.
Min Heejin, who was rising in SM at that time, would have heard the stories. She knew how Bang started, from just a mere composer to a partner and then a company owner, and I think she expected her arrangement to be similar to what JYP had with SIdus and Bang had with JYP.
In addition, there was a recent incident where someone with no stake in a company did become a company owner.
In 2020 a Lee Jieun, who owned no major stakes in Kakao Entertainment, was given 30% of its shares, and Bae Jonghan, her manager, was given 30%, controlled by Lee Jieun. So, at the age of 27, Lee Jieun became the Owner of Edam Entertainment, with Kakao owning the other 40%, and Lee Jieun claimed the earnings of the singer IU exclusively. Only the cost of IU towards various outfits of Kakao was paid to Kakao Entertainment, and Lee JIeun claimed all the profit.
I think Min Heejin might have been made upset by the cold fact that while Min Heejin brought significantly more revenue to Hybe than Lee Jieun did to Kakao when the latter was the owner of Edam Entertainment,
Min Heejin saw how Park Jinyoung, Bang Sihyuk and Lee Jieun got rich, starting from nowhere to become owners.
A mere manager only can make so much while an owner claims everything.
\\\\