Van Gogh's Dr. Gachet painting hide ans seek story; art as commodity

The right painting is missing. 
Van Gogh had given it to Dr. Gachet* and the painting is having a very difficult existence.  
Sold for the first time in 1897 for £300 it was confiscated in 1930 by the Nazis as degenerated art, found in 1937 to be sold in 1938 by a greedy Goering**, known as an art thieve, for $53 000 and last seen in an auction in 1990 being sold for $82,500,000 to Ryoei Saito a Japanese art lover that wanted the painting to be cremated with him. He died in 1996 and the painting was not cremated but it disappeared.
This price Saito payed made the painting be the number four at the top ten most expensive masterpieces what is ironic when we remember that Van Gogh didn't sell any painting during his lifetime and lived asking money to his brother.
Now, thanks to a crazy art dealer the painting is missing. Many questions arise from this occurrence being one of them: have art became a commodity? to whom masterpieces belong? 
The left painting is the copy Vincent has made to himself and is now at the Musée d'Orsay, Paris France.
In a letter to his brother Van Gogh wrote about Dr Gachet's painting:

"I've done the portrait of M. Gachet with a melancholy expression, which might well seem like a grimace to those who see it... Sad but gentle, yet clear and intelligent, that is how many portraits ought to be done... There are modern heads that may be looked at for a long time, and that may perhaps be looked back on with longing a hundred years later." 

"What impassions me most- much, much more than all the rest of my métier – is the portrait, the modern portrait. I seek it in color, and surely I am not the only one to seek it in this direction. I should like – mind you, far be it from me to say that I shall be able to do it, although this is what I am aiming at – I should like to paint portraits which would appear after a century to the people living then as apparitions. By which I mean that I do not endeavor to achieve this by photographic resemblance, but by means of our compassioned expressions – that is to say, using our knowledge of and our modern taste for color as a means of arriving at the expression and the intensification of the character."

"So the portrait of Dr. Gachet shows you a face the color an overheated brick, and scorched by the sun, with reddish hair and a white cap, surrounded by a rustic scenery with a background of blue hills; his clothes are ultramarine – this brings out the face and makes it paler, notwithstanding the fact that it is brick-colored. His hands, the hands of an obstetrician, are paler than the face. Before him, lying on a red garden table, are yellow novels and a foxglove flower of a somber purple hue. My self-portrait is done in nearly the same way; the blue is the blue color of the sky in the later afternoon, and the clothes are a bright lilac.” Letter written in 5 June 1890.

*Dr. Gachet is the doctor who took care of Van Gogh during his stay at the doctor's home in Auvers-sur-Oise.
** Goering was the Commander-in-Chief of the German Air Force sentenced to death at Nuremberg trial. He committed suicide before the sentence was executed.