Writing for money and reservation of copyright are, at bottom, the ruin of literature. No one writes anything that is worth writing, unless he writes entirely for the sake of his subject. What an inestimable boon it would be, if in every branch of literature there were only a few books, but those excellent! This can never happen, as long as money is to be made by writing. It seems as though the money lay under a curse; for every author degenerates as soon as he begins to put pen to paper in any way for the sake of gain. The best works of the greatest men all come from the time when they had to write for nothing or for very little....
https://www.gutenberg.org/files/10714/10714-h/10714-h.htm#li...
Brain Pickings articulates my reasons well, though really, just read the source:
https://www.brainpickings.org/2014/01/13/schopenhauer-on-aut...