From 1997, SM was dominant in KPop.
The dominance only ended, because of BTS, although a Senior Singer, who spent her entire career fighting SM, helped.
But 2021 is the year of the resurgence of SM, with Aespa doing pretty well and becoming the foremost girl group of the 4th generation, stealing initiative over the new upcoming Hybe girl group (which will be hated to the hilt by GFriend's fans, who will do whatever to undermine it),
while NCT Dream sold more than 2 million albums.
The NCT system was finally established, which means SM can change the members as it feels like and maintain the NCT system forever.
txt and Enhypen have not reached the level of NCT yet, and if BTS stumbles (SVT is around the same age as BTS), NCT, aespa and SM will regain the top position of KPop.
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Idol business is selling the idols to the people, and since SM was the premier company in KPop for so long, all the best talents knocked SM's door first.
While JYP excels in girl groups and Big Hit, now Hybe, produced BTS, still the image of SM being the premier company is strong which is why it still gets the first choice of trainees.
As long as SM gets the first choice of trainees, the dominance of SM is going to continue, and in 2030 the whole BTS thing might be forgotten and 78 years old Sooman Lee, his sons and Susan 'Sunny' Soonkyu Lee, most likely an SM exec by then (both of her sisters are execs in SM), will watch NCT 18th iteration which has sold the most albums in the world on 2029.