Self-published authors can earn 40% to 60% royalties for the selling price of a book, while traditionally published authors typically earn 10% to 12% royalties. First-time authors willing to publish traditionally will receive a prepayment. This is usuallyR$10,000 (not so much for first-time authors).
It has been estimated that King earns betweenR$1 andR$3 for each of his book copies that are sold. As he has sold over 350 million copies of his books worldwide, it would make sense that he has such a large net worth.