Sherman Alexie's father was an avid reader and this heavily influenced Sherman. He began to pick up books at a very early age and was a completely self taught reader. This in itself is very impressive, but even more so considering that he was Indian. Sherman mentions that a "smart Indian" is a dangerous person. Education is such a powerful thing. By simply reading, you're able to expand your overall knowledge significantly. This allows you to go beyond what you've been taught because you begin to learn about new things and concepts. This is influential especially in a person like Sherman.
He was not only feared by non - Indians, but also by people of his own kind. When you're ethnically different, and by this I mean not caucasian, you're expected to have a certain amount of knowledge. A very minimal amount of knowledge. Sherman was expected to be like any other Indian that struggled with school related matters. He was different though and being different can be a threat to many. Once you've proven to be smarter and hungry for knowledge, you're a force. If you lack resources and books, you can be kept under control without asking questions. By reading, Sherman was likely to want more than he was given because he knew what else was out there. A "smart Indian" is bound to question authority and likely to crave education.