It is in a niche genre (idol stuff) and yuri (or yuri-ish at least), but not the typical yuri story either. It doesn't really try to appeal to the lowest common denominator.
I'd argue that it's the same genre as some fairly successful works like Death Note & Classroom of the Elite, the Idol elements are just set dressing, making it an "idol story" in the same way that DN is a detective drama or COTE is a school drama. 'Cause, like, we all know that this manga isn't an accurate depiction of what idols are like. (Plus, Oshi no Ko got pretty mainstream despite being more of an idol story than this.)
And the GL stuff isn't too big of a problem, I think, 'cause it's not like the story's a romance or anything, and it's pretty easy for people who don't like it to just handwave it away like "she doesn't
actually love her, she's just her fan! It's an important piece of Japanese culture that really has no western equivalent, so it's only natural that westerners would culturally appropriate it and call it love!" It's happened before, I see no reason why it can't happen again.
So, personally, I feel like this
does have the makings of a pretty successful mainstream-adjacent manga. Though I do agree with what you're saying at least in the fact that I feel like the idol framing is probably causing some potential readers to drop it before getting to the point where that "scheming genius drama" actually comes out.
I think that if it ever got an anime, though, the lower barrier of entry would allow more people to get past that hurdle, at which point I definitely think it could have a chance at blowing up. At that point, it'd just a matter of luck, but I think it'd have a good 60~70% chance, which is better than I'd have given some of the stuff that's been successful lately.
Though I could also totally be reading this wrong and maybe this is totally set up to be a flop. What do I know? The last time I learned anything about economics or market patterns was in my Highschool AP Economics class, and I honestly did not pay attention in that class in the slightest.