If the value of a work of art comes from the work of the artist, then it makes no sense for it to gain value after the artist's death when he can do no more art or any effort to be noticed. There has to be something more to it than that.
I'd love it if artists sold their art at a price that was directly related to the quality of their work, but it's obviously not the case. Many hard working, talented artists die poor, while some talentless hacks become rich. There has to be something more than artistic skill and hard work involved.
A few years back, a painting
initially attributed to a German painter was attributed to Leonardo da Vinci. The painting's value multiplied by several orders of magnitude. If it turns out it's not by da Vinci after all, the value will go down. It's the same painting, so why does the value change? It's not because the painting becomes better or worse.
Like it or not, there are market forces that influence the value of your work that have nothing to do with artistry, "the discipline to present a vision of his work" or even the artist's work to be noticed. Understanding those forces can mean the difference between being poor and being rich, doing the same work. I have no interest in being a starving artist, so I'll keep trying to understand those forces.