I left the JWs in 1984 and had lots of Watchtower books, including the bound volumes going back to 1960. Also had Russell and Rutherford's books, which I kept. Since I left voluntarily and was not DFd, I was able to sell my bound volume set to a new elder, plus some extra copies of older books that I had on hand. Couldn't see burning or throwing the books away, when there were people willing to pay for them.
In the 1990s I sold a NWT 5 volume set to a second hand bookstore for twice what I originally paid for