They believe that they will and therefore we need to ask is their governance structure fit for purpose if they achieve their goals?
There's absolutely no reason to believe OpenAI is right about this when thousands of experts have been wrong. AGI is deceptively difficult because it's almost impossible to see how far away you are from the goal. You can see how far you've come and extrapolate, but that's always a mistake.
It has been done for weapons, it has been done for cryptography in the 80s, it has been discussed for vaccines during the pandemic, it has been done for finance and surely it will be done for AGI.