Why would you publish a book yourself?

Cory Doctorow:

But, as with any arts venture and any entrepreneurial effort, the realistic odds are that you’ll be one of the people whose efforts fail to shake the world. The realistic odds are that you’ll earn more working a regular job in an office than you will trying to invent fictional worlds and then invent new ways of selling them. There’s only one good reason to do that kind of thing: because it makes you sane and whole and happy.