This article lists out why it's not good of an idea as you think.
>Universities’ endowments are not as much help as their billion-dollar valuations would suggest. For a start, much of the money is reserved for a particular purpose, funding a specific professorship or research centre, say. Legal covenants often prevent it from being diverted for other purposes. In any case, the income from an endowment is typically used to fund a big share of a university’s operating costs. Eat into the principal and you eat into that revenue stream.
>What is more, eating into the principal is difficult. Many endowments, in search of higher income, have invested heavily in illiquid assets, such as private equity, property and venture capital. That is a reasonable strategy for institutions that plan to be around for centuries, but makes it far harder to sell assets to cover a sudden budgetary shortfall. And with markets in turmoil, prices of liquid assets such as stocks and government bonds have gyrated in recent days. Endowments that “decapitalise” now would risk crystallising big losses.
More worrying is the fact that the federal government can inflict even more harm aside from cutting off federal funding:
>the Trump administration has many other ways to inflict financial pain on universities apart from withholding research funding. It could make it harder for students to tap the government’s financial-aid programmes. It could issue fewer visas to foreign students, who tend to pay full tuition. With Congress’s help, it could amend tax laws in ways that would hurt universities.
https://archive.is/siUqm