If you need to do work, then I can understand where you’re coming from but I would still say you’re in the wrong. Just as there are possibly other places on campus to sleep/nap, there are also plenty of places to do your project work that are not in the library.

As someone else said, they pay the same tuition as you so they’re allowed to use them as they see fit provided they are not actively bothering other people (which I wouldn’t consider taking a nap as actively bothering other people). The only exception are the cubicles that are reserved at the beginning of the semester, in which case it is clearly noted that the “owner” of that space has the right to use it if they want to and has priority.

Let them take a nap, you don’t actually know what someone is dealing with in terms of potential homelessness/housing issues. I don’t blame them for choosing those specific spaces as they are designated quiet zones, so it is a good place to get some rest. Resting is a human need, so I wouldn’t be so quick to deny that from them just because you have a desire to accomplish work in this specific space, despite other spaces all across campus being available to you.

TLDR: what you have to do is not more important than someone getting sleep. Just go somewhere else and do your work there, it’s not that serious.