What would happen if Zion Williamson chose MMA over the NBA?

6'7, 275 lbs of pure explosiveness. Only 18 years old. I can't remember a player from any sport that has been hyped up as much as this kid coming out of college. And for good reason. Obviously he would have no reason to chose MMA as he will make hundreds of millions playing NBA, but in a hypothetical world where he did, how would he do? With what Ngannou did was almost no training I would imagine Zion would quickly become the greatest fighter of all time. He's an A+++ level athlete like MMA...

What would happen if Zion Williamson chose MMA over the NBA?