You're overthinking it. Supply and demand, my boy, it isn't limited to artists selling shit to an audience. Animators primarily sell to networks who sell airtime to marketers (yes, even streaming, except now they charge you less than cable for the right to get advertised to)
The networks aren't demanding enough shows to justify an over supply of animation talent for original content. However, there's plenty of demand for animation on the advertising part of the industry, because its the less savory part no one really wants to get into as art college kids. Now, on paper there should be a demand from the audience for original animation, but here's the thing: even in japan, most anime is actually just advertising manga, original anime are the exception, not the rule. But on top of that anime is basically this spiderweb of cross promotion and a history of people sitting down and promoting the medium in niche circles AND the government directly financing some of the bigger projects like akira.
In the west, comics don't really sell as much as manga does in the east. They don't justify being something that gets a ton of marketing. Likewise, when they do sell a lot and get adaptations, there's no culture of comics and animation collaboration or cross promotion, so they just act like traditional writer pitches and sell to the live action industry. So basically, lacking the self sustaining niche economy of fostering most of the risky creative stuff in comics and then adapting it to animation, which in turn creates a demand for original animation, it means there's basically no demand even from the niche audience for original animation.
You know what does get demand? videogames. Like it or not, Videogames have made western animation as a commercial product obsolete for anything besides children's media. Most animators worth their salt eventually move into videogame development once they realize it makes more money and lets them be more creatively free.