The irony.
This ends up being a failed drama about a failed idol group.
Similar to the idol group in the story, this drama did not get the support it deserved, almost no promotion and shown in a late night timeslot, not optimal for the target audience of this drama.
But unlike the story, there is no fairy tale ending as ratings continued to suffer. It is disheartening to see that all the efforts put in by the cast and staff went unwatched.

For me, it is a very underrated drama, and I like the fact that most characters were played by real idols. All except Stella in Cotton Candy are real idols, and it makes it so much more convincing. The singing and the dancing were good as expected. Most of the cast in Mars are trainees or having previous auditioned for idols or survival shows.
It gives you a glimpse of the reality of the fate of most idol aspirers, which is failure (I think the stats given in the drama is that there are about 320 idols / 60 groups debuting EACH YEAR in Korea, and how many of them become successful?)