It makes business sense as well. It doesn't make much sense to build an entire company around the idea that OpenAI's APIs are always available and you won't eventually get screwed. "Be careful of basing your business on top of another" and all that yadda yadda.

If you want to build a business around LLMs, it makes a lot of sense to be able to run the core service of what you want to offer on your own infrastructure instead of rely on a 3rd party that most likely doesn't give more than 1% care about you.