Excellent article on the benefits of self-publishing, "Scribblers are doing it for themselves".
Your book may attract the attention of a major publisher:
It does happen. Look at GP Taylor, author of the children's novel Shadowmancer, which was bought by Faber in 2003. He now has a £3.5m six-book deal, and a film deal worth millions. The American rights to Shadowmancer were sold for £314,000, rumoured to be more than three times JK Rowling's cheque for the American publication of the first Harry Potter story.
Taylor, was a 43-year old vicar in Cloughton, North Yorkshire. He was advised that no publisher would touch his tale of good and evil set on the North-East coast in the 18th-century. So he sold his motorbike and published Shadowmancer himself for £3,500.