There is no such thing as a "free" education, especially at the graduate level. Even though MIT does not have tuition, students are still responsible for paying fees, room and board, and other associated expenses. In addition, most graduate programs at MIT require students to either teach or do research in order to receive a stipend, which is used to help cover these costs. So while it is possible to attend MIT grad school without paying tuition, it is not possible to do so without paying any money.