I don't know if I would call it hoarding for retirement. I stock up on books when they are on sale. Now I only get books I would have bought anyway, but it does save me money that way. I don't care if I read one of those books 3 years after I buy it. It doesn't have an expiration date on it and now with ebooks, I don't have any storage issues either.
For me, my tastes don't change as much so I'll still want to read those books years down the line.
I don't have to wait until retirement for money to be tight. Its already like that. So library, books on sale, that is how I do it. Do I buy more than I read right now? Of course.
. But then I have always had more books around me than I can read. I think many readers are like that.
I could stop buying a book today and still read for the next 3 or so years I think. But where is the fun in that.
