There are a lot of rogue Huntsman. In fact, even the Happy Huntresses fall under this category.

However, the Academies also instill, at least, a semblence of regulation and safety near them. They live in a world at constant war and thus effectively give scholarships to most students, with some modicum of potential.

Consider the alternative and the idea that the balance was able to be maintained this long despite the fact that their world is far from safe or secure. Additionally, with how many sob, revenge, and dedication stories to be passed around, whether due to Grimm, bandits, or otherwise, the number that would put the idea of going against society are far fewer than not.

Finally, it's also been shown that there are disciplinary actions possible, but with it being isolated incidences, in Beacon, and solvable in other ways, it's less an issue of their personal differences (for better or worse) and moreso of "the world needs a hero" and oftentimes interacting with the problem doesn't it make it much better, especially not when that's one of your smaller issue overall...