The internet has killed the need for many cookbooks and do it yourself type books, we live in a YouTube world.
I have a couple hundred cookbooks but when I want a recipe it's easier to do a Google search and find what I need. I only read the cookbooks when I want to share the writers experiences and get a feel for how they lived, celebrated holidays, etc...
I also have about 1,000 books on local history that used to have some value as collectibles and antiques, those books have lost a significant amount of value since the print on demand services started scanning copies and reprinting them or putting the text on the internet for free.
It is definitely a changing world where books are concerned.
I am working on reducing the number of books, the easy ones have already gone to the Salvation Army, this summer some of the scarce older books will go to a charity book shop with the hope that they can make a few bucks and a few will get foisted off on friends and kindred spirits.
The hardest part is not buying/rescuing interesting books that I see at the local flea market.
Note to self, If you find yourself standing in the bottom of a deep hole, stop digging, LOL!!!