Why did Rick Riordan stop writing Percy Jackson books?

Rick Riordan did not stop writing Percy Jackson books. He has written five books in the original Percy Jackson series, two series of five books each featuring different characters from the demigod world (The Heroes of Olympus and The Trials of Apollo), and numerous companion books, including short stories, novellas, and guides. Rick Riordan is still actively writing books and has announced plans to write additional Percy Jackson-related books in the future.