I read/listen to lots of nonfiction books(30 so far this year) and the only benefit of buying books instead of using a Library is being able to write notes in them.

With digital copies I'll screenshot a page.

Not sure what is better, both seem to have their problems. Underlining requires flipping through every page. Screenshotting gives you more and less information than you need.

But library digital books are free and don't require transportation to obtain.

As a side note, read science, history and philosophy books. It's mind boggling how much better these books are than social media. If a book sucks, move onto the next one(or tell yourself you will read it later).