I'm old enough to have seen that a breathless "the real secret to Stradivarius's violins discovered!!!" story comes up about once ever ten years, then fades away, making way for the next iteration.
When I was in high school it was that the wood he used was floated down rivers before it got to him, and therefore picked up minerals - which a modern maker claimed to have duplicated by boiling the wood in a broth made from shrimp shells. (I'm not making this up.) Earlier, it was something to do with the exact composition of the varnish. And no doubt numerous others that I never heard of.
Somehow, through it all, Strads are still prized above all other instruments, and keep increasing in value each year.
Life is a healthy respect for mother nature laced with greed.