5 years at $20 million equals the highest paid FIFA player’s single year pay (or Tom Cruise’s pay for one movie, Top Gun: Maverick), or about two years of the highest paid NFL players, so it won't catch up the their wealth over that time (assuming similar lifestyle) as its losing ground to them every year.
(And the claim was total, not per person, salary, anyway.)
99% chance it's made up.
That said, if they thought a specific individual had even a reasonable chance of coming up with an improvement on the current state-of-the-art AI architecture that they'd be able to keep entirely to themselves, $20M would be a massive bargain.
The rumor is still almost certainly fake, but for someone very specific at this critical time in the field, I don't know if the number would be that absurd.
I’d pay creator of GPT that money easily. Probably not anyone else
I guess the reason why AI is so interesting is that human stupidity is so widespread.