He was more famous because he appeared on TV, and transfered/the joy of painting, not because of his paintings. They were unremarkable to say the least.

A lot of people are trying to make a living painting landscapes with the same painting for dummies style that Ross used (not invented). It seems counterproductive to give money to speculators for an unremarkable painting of a dead man when you can spend a fraction of that to buy a similar decorative painting and contribute to the income of someone who actually worked and spent time on it.