The earthquake victims will be helped if people buy the book. I feel slightly less selfish about wanting to be a writer now that I have contributed to this.
Writing is a solitary and single-minded thing to do. Writers can become obsessed and insular. They feel guilty giving so much time and attention to writing, especially when it isn't easy to make a living out of it. The creative rewards are always there for the writer, but it is nice to see that sometimes the financial rewards can be there for other people as well.