Methinks the appropriate response to this claim is "hogwash."
Napa Valley just isn't that big.
By volume it produces only about 4% of of CA's wine, much less that of the whole country.
http://thirstyreader.com/for-wine-geeks-only-napa-valley-by-the-numbers/
The dollar value of Napa wine is higher. 2013 earned growers $638M. Total US is somewhere around $2500M, which puts Napa close to 25%.
I'm no expert in this field, so the two statistics might not be directly comparable.
Seems unlikely to me that roughly 3% of the crop would earn 25% of the dollars, but then wine is different from other crops.
“...he only lost three barrels, but they were a “top quality vintage.” ........
It was insured for HOW MUCH?
The author has a DRY sense of humor...