This is part of the reason why "mental illness" is a broken term for certain applications. Unevenly-matched skill (coping, etc) vs. circumstance (group psycholo

This is part of the reason why "mental illness" is a broken term for certain applications. Unevenly-matched skill (coping, etc) vs. circumstance (group psychology, social standards) is one alternate POV that better explains why a "mentally-ill" person could create genius works. They have become conditioned to exploring extremes by dint of circumstance and personal history; their liabilities, struggles, and even periodic victories in these contexts allow them to produce works the likes of which are rarely seen or even contemplated in "non-genius" company. The audience knows intuitively that they are experiencing some fundamental truth, though they cannot in a small number of steps arrive at the sequence that allowed the truth to emerge.