Letting go

Aged about 18-20 I was this lonely boy who loved Barbra Streisand. So I collected all the stuff I could find about her, meaning many years later I own over thirty books about her and other stuff besides. The thing is, it is all in a box and never looked at anymore. I no longer cherish this stuff. Idealistically I would put the lot of EbAY and watch it fly away and receive some cash. But I know I am never going to do that- I don't want to be working out the postage costs for a start. Last September I asked the vet to euthanise my beloved elderly cat, despite the vet offering a treatment plan. How come I let go of my bestie so easily yet this dusty pile of books is making me anxious? Should I just do it , take them to a charity store? Have you collected things and later found them a burden? I shall never collect vast amounts of things again.