It has taken me a long time to realize that renting books is the way to go for most books. The frequency with which I go back to a book is so low that I don’t really see any returns on permanent possession that accrue from the ability to go back.
Renting also has the virtue of disciplining me: I rent when I am ready to read and it incentives me to finish the book (or graze and assess whether the book is worth finishing) before the rental period expires.
For e-books, my format of choice, buying a book is even less attractive. One reason why people buy a book is for the social returns from displaying the book on a bookshelf. E-books don’t provide that, though in time people may devise mechanisms to do just that. Another reason why people prefer buying books is that they want something ‘new.’ Once again, the concern doesn’t apply to e-books.
From a seller’s perspective, renting has the advantage of expanding the market. Sellers get money from people who would otherwise not buy the book. These people may, instead, substitute it by copying the book or borrowing it from a friend or a library or getting similar content elsewhere, e.g., Youtube or other (cheaper) books, or they may simply forgo reading the book.