See my post above. Millions earned in licensing fees from drugs developed in a lab on campus. Millions in rent, development fees, even “air rights” when a university sells off the space above a two story building to a commercial entity who can then build a 12 story building, depending on the zoning. Universities own a part of the intellectual property developed by its faculty and researchers- so parts of the royalties on books, recurring revenue streams on technology patents or medical devices, etc.
There is a financial aid budget. And that budget has some components of dedicated funds (at my 40th college reunion we specified that our class gift go to create an endowment for financial aid for first gen disadvantaged students). But there are unrestricted funds which support the general operating budget of the U-- snow removal, landscaping, and yes, financial aid.