They physically would be unable to sleep or stay awake in the normal rythme needed to keep such a job in the first place.
I don't think you understand what a disorder is.
It's not something you can just choose to not have because it negatively effects your life.
People with non-24 are physically unable to stick to such a schedule no matter how much they would like to or what the negative effects are. They can't just brute force it for the sake of wageslave reasons.
And no, not even the thread ot poverty or losing their family would be enough for them without treatment to be able to follow such a schedule.