You are asking us here to determine the reasons why an accomplished and so creative writer creates such great stories. Well, Stephen King used to write short stories when he was a young boy (her grandmother used to pay him every time he would finish a story), so I can almost answer one part of your question: He had already started to improve his writing skills and creativity since that particular period of his life. These old writings had an impact on his own personality, and they created a strong belief inside him, that provided him with another strong ambition to become a writer.
Also, as Stephen King has claimed, inspiration is everywhere, it is something you find in front of you every minute of your life.Especially if you are a writer, he says, you see things differently.And, if you are good enough, you will recognize that inspirations are just reflections of new worlds, worlds that are waiting for you to develop them and show them to the real world.
Stephen King had faced a lot of difficulties while writing. He stared writing his very first novel, ''The Dark Tower'' at the age of 18 or 19, but he did not wish to get it published just yet. His very first published novel was ''Carrie'', if I am not mistaken.That masterpiece had gotten neglected by amajority of publishers, who denied to admit how gifted he really was that time.
Stephen King is a great writer. He is gifted, because he was meant to become an author.
Somethings are just lucky, some other things need talent in order to be succeeded.
~Passionate fan of Stephen King for more than 8 years~