There a few books I started and never finished. Leaving a book halfway has always been frustrating to me, because I felt utterly wrong giving up on a book. Books always had a sort of sacred halo around them.
From the Sacred Library in Assisi, where I touched 500 years old ones, to the Kindle store, where they do not exist until you click, books are fascinating things.
I remember when as a teenager there was no way I could browse a bookstore and leave empty handed. That accumulated books I will never read. I moved house and dragged them along with me over the years.
Books are not meant to be lent, they are trained to never come back. Better give them away as a present and eventually buy them new again. However I have never give away any of my books so they kept on stacking.
The digital era came handy, allowing me to hoard books without adding matter to my shelves. Nevertheless I kept accumulating, reading way less than I should.
The best book ever is the one you read over and over. If a book does not worth to be read a second time, it probably did not worth to be read the first time either.