They painted but who made money?

Did the masters like Monet, Manet, Degas, Van Gogh make money out of their paintings? When we google their names, we find them described as famous artists. True. They became famous. But when? Their artworks turned worth multitude of millions of dollars. But did they earn even a living out their paintings?

Of course, Picasso became rich. Matisse became famous in their lifetime. What was the mystery of their quick success?