What Dilbert is saying is that salaries paid in his company are really ridiculous, implying that the artist does not make even a minimum with his art, which in itself means that he's not selling at all. The artist says that he doesn't need to sell, but isn't Wally right when disputing the worth of an art career that is not being welcome by nobody else? Bottomline: you might do great art, but the title of artist depends of acknowledgment by others.
Sorry but it is true.
And i am pretty doubtful about Van Gogh, apparently most of the success of Van Gogh part when some guy invented a sad history about a unknown artist that died decades ago.
A pity to get all sensible about a comic strip, I know, but I don't think it has been established that his art is terrible at this point. Dilbert assumes it is without having seen it and Wally then makes a statement that is obviously not true without having seen it.
May be the reason why this guy's art is terrible is because he has a proper job instead of contributing full time towards art. Like many "artists", he can still dream though.
What a load of rubbish. Even a comic artist should know better than that. Geez, was Van Gogh a terrible artist? The general opinion is that he was not, but he had to count on his brother for money.