Make the books that people need abundant
The University of Cambridge has a fantastic library system, which is worth studying. In the UK, it is not expected that students will purchase their textbooks, which has benefits from the perspective of access. Thus, the libraries (every department and college has one) see it as their duty to provide enough textbooks that each student can use one. For the largest classes, this means maybe ~3 copies per 10 students in the class. The libraries then serve as hubs of academic life, for meeting and discussion and study.
The MIT libraries could learn a lot from this. If you provide the textbooks that people need (in physical format), students will use them, and the libraries will become much more important in academic life than they are at the moment. This will also take financial pressure off of students.
Physical collections should be supplemented with digital collections, as well, but many students will still prefer a physical book to a digital one (they are still simply easier to read), and if the library only provides digital collections, it may struggle to attract students to its physical location.
Libraries at the University of Cambridge were wonderful places to work; they were open 24 hours a day, and they combined excellent work spaces with the resources and books that I needed. At MIT, the libraries have very limited collections and they are open at extremely restrictive hours, and as a result, I do not think about them when I am considering where I can find the books that I need, or where I should go to study.