I would happily read a paper version of a book if someone had a copy of something that they wanted to recommend and lend, thereby saving me having to buy a copy.
That would probably be my only regret in purchasing electronic books; that I could not readily lend them to my friends.
I think you can lend some Kindle books, maybe other readers as well. Of course, your friends also have to have a Kindle. I am not sure if this works if friends have a Kindle app, and not a Kindle reader.
Works both ways. The borrower can read with a Kindle or the Kindle app.