The story
The figurative sense comes from the notion that the writer's or artist's output is enough to provide sustenance; compare breadwinner, put food on the table, and keep the lights on.
Etymology from Wiktionary, CC BY-SA 4.0.
pot boiler
Today it means: A creative work of low quality (book, art, etc.), produced merely to earn a living or for profit, as opposed to serious creative expression. Full definition →