I can't explain why but I don't think money is it. Nor a new project or whatever can't be it either. Its just too small of a value proposition when you are already in openAI making banger models used by the world.
According to reports, the comp packages were in the hundreds of millions of dollars. I doubt anyone but execs are making that kind of money at OpenAI; its the sort of money you hope from a successful exit after years of efforts. I don’t blame them for jumping ship.