Nowadays maybe ten understand (being facetious).As Sheldon Cooper would say “fun fact, Einstein never held a PHD”
When he turned his dissertation in, they ultimately gave it back to him with the words “fanciful and irrelevant written in large red letters”
Only about 7-8 people all over the world understood what he was saying at that time.
And as they say, “and now you know, the rest, of the story”