"It is not easy to start advertising using OpenAI technology, as Facebook would need to spend years and years."
Why? They have all the material for teaching it on hand, for free, full access. It won't take more than weeks once they get it running and it's limited only by cpu/disk power they bother to let it use.
By "annotation" you need *manually* doing something? That won't happen: Either is fully automated or it doesn't happen.
I do agree on motivation, but there's no way they'll waste years to do something manually.