By the time I was 12 or 13, I was studying biochemistry textbooks.
I'd like to put in a vote for the intrinsic fascination of science.
I was a bad practicing physician because I was never sure of the diagnosis or of the treatment.
I don't believe anybody can really grasp everything that's even in one textbook.
I got my Nobel Prize for my lab work.
If it takes you 20 or 25 years to establish yourself in one field, you really ought to be careful not to stray too far.