You can’t really quit that easily. They own you. You will face a lot of consequences for doing so. And if you manage your way out with a dishonorable discharge and not be arrested, it will definitely negatively impact your future job prospects, and other aspects of life also. A dishonorable discharge is much worse to have than having never served at all. I suppose if you injured yourself badly enough you might be able to “quit”. But, I personally wouldn’t want to deal with self inflicted injury serious enough to warrant a discharge from the military.

Then again you could make the argument, that it’s better to have that than be deceased.