Most U.S. trained professors are from a few elite universities

As I said, not nearly all Masters must have Master's degrees - e.g. Master Sergeants - only about 9% have Master's degrees.
https://www.zippia.com/master-sergeant-jobs/education/

Back in the 80s you could be a Grand Master (e.g. Flash or Melle Mel) with no degrees, just a couple of turntables and a mike. You can still be one - but now you have to be really good at chess.

https://en.wikipedia.org/wiki/Grandmaster_(chess)#:~:text=At least 50% of the,include the player's own federation

Credential inflation has struck in the chess world. There are now Super Grandmasters, referred to in the link. I hope that's nothing like a WIDU "Grand PhD."

 

When the International Frisbee Association was a thing, I held a Master rating. Above Expert, below Grand Master.

 

Thanks, dad. Oh, wait, wrong Jedi. They all look alike in those robes....