No writer should say, "I am writing for me. I don't care who reads it." Because anyone who says this is either--
talking about a personal journal
never read a book and thus has no concept of the author/reader relationship
is participating in NaNoWriMo
The READER is king in the writer's world. It's all about connecting with the READER. A writer should have the READER in mind as he writes. Stephen King has often stated that his primary reader is his wife Tabitha. He writes with her in mind as his audience. He knows if she gets it, then his demographic will, too. She represents his demographic. Tabitha King has made her husband a best-selling star among authors.
Who is your READER? Who do you write for, or think about as you work, perhaps even chuckling to yourself as you type out a scene, "Oh, yes, she is going to love this part"?