I don't think anyone is arguing that the consumption is illegal. It's the reproduction that is illegal.
Read a book, that's fine. Write a book, that's fine. Read a book and then write a book that is 99.9% the same as the book that you read and sell it for profit without a license from the original author, that's infringement.
Read a book, that's fine. Write a book, that's fine. Read a book and then write a book that is 99.9% the same as the book that you read and sell it for profit without a license from the original author, that's infringement.