The parasocial intensity is something else.

Stans (who take their name from Eminem’s song “Stan”, where it wasn’t a positive association) get quite intense, to the point of breaking and entering private property, stalking and causing road accidents, writing messages in their blood, even poisoning them, and that’s just the “selected incidents” on Wikipedia. https://en.m.wikipedia.org/wiki/Sasaeng_fan

No, stans don't get that intense, it's literally a tiny crazed subset - ie the Saesangs.

Every fandom of any type of a certain size has insane fans (looking at you sports teams and fans).

I think there was an enormous amount of innovation and ingenuity required to broaden a market so narrow that it only included preteens to the entire globe across all sex, age, and cultures.

I understand your point but there’s more interesting analysis here than “this is the same it’s been done before.”