Carl, you wrote an article (informative) not an essay (argumentative). Among the many good facts in the paper are the outrageous sums for dead artists' works. As you pointed out, when an artist dies, the body of work isn't getting any bigger, unless the artist was smart enough to stash paintings in a warehouse or rented storage (I remember reading that Hemingway stashed some manuscripts in a safety deposit box and one was 1k+ pages that an editor turned into a 300+ page bad book). 

Point here is that you need a point: Why do the prices of paintings soar after an artist dies? This would certainly discourage me from painting. The simple answer is that a lot more people now have a lot more money and since they cannot hunt rhino in Africa anymore they "shoot" for artworks, i.e., I cannot put a big rhino head that is bigger than yours on my wall, so instead my Picasso is more expensive than yours, though yours might be a better painting, according to experts. Art is nebulous. I know within three seconds if I like a painting, no matter the artist.

So make a statement: $100 million for any painting, even if by the hand of God, is absurd, as the money could be allocated elsewhere—perhaps charity. There is a thesis: great artworks owned by charities, thanks to someone's donation. Or, why do churches have masterpieces in their vaults and beggars at their front doors?

Track a big art sale: follow the money. The seller gets a pile, the buyer loses a pile, the auction house gets a cut. The economics are net nothing: the money just sloshes around actually not doing any good. The painting moves from one wall to another wall. The world turns and this transaction makes no great difference at all. 

The Mona Lisa is just an old painting of an ugly woman, so what is it "worth"? Nothing, unless some Arab tycoon or Chinese Communist Party leader, both of whom probably stole most of their money, agrees to pay $1 billion. That's what they think it's "worth." I think it's an old painting of an ugly woman: $0.

The cavemen who drew wonderful pictures on cave walls in France a zillion years ago didn’t get a penny for their efforts, just a lot of admiring looks from the cavewomen. Maybe that was worth something.