A lot of what inspired the villain in the Shark House is the fact that he never can win against the main character, while Razzmatazz gave into the darkside, Minami didn't.

Minami is the go getter friend in the Tomozaki series who wants to beat Aoi Hinami, no matter how much she tries, she can't beat her at anything from athletics, academics to even politics.
This actually causes her to quit, even though it wasn't for very long it started to eat away at her to the point that it would cost her, her friendship with Hinami, she hated what she was thinking, it felt disgusting to think of her friend like that.
Some of what Minami said in the build up to her quitting have some sense to them, "no one remembers second place" being the standout.
We know that Hinami's drive to be the best comes from the need to beat Tomozaki at Attack Families, so the journeys of both characters run parallel to each other.
Competition stops being fun when you start thinking the winner should disappear, happens way too much in sport and gets even worse with content creation and even the working world, envy is a very dangerous sin and Minami had enough sense to stop before it corrupted her.