It’s much easier and cheaper for the average person today to build a product on top of an existing LLM than to train their own model. Most “AI companies” are doing that.
There are a lot more models than just LLM. Small specialized model are not necessarily costly to build and can be as (if not more) efficient and cheaper; both in term of training and inference.
Another way to put it is most people building AI products are just using the existing LLMs instead of creating new models. It’s a gold rush akin to early mobile apps.