I'm not into first editions unless they're very reasonably priced, but I like having lots of older books in descriptive notation or languages that I can read or figure out. I also have many/most of the McFarland, Caissa, and Edition Olms books of the players and tournaments I'm interested in. Probably have about 400-500 books all told. But for most books, I'm happy with a reissue vs. a pricey first edition. The one first edition that I'd be tempted to buy but know I would not be able to afford and find in good condition is one of the numbered copies of the Sixth American Chess Congress 1889, edited by Steinitz. I saw it in pristine condition in a Chicago Library and I really wanted it. So I console myself with the very small, hard to read Edition Olms reissue.
My problem is that I have too many books which I need for my research on human evolution and history of evolutionary ideas. I simply don't have much space at home. I would like to sell part of my collection, also boards, sets and clocks. It doesn't make sense to have things which can't be displayed.
My stuff is not for investment or display. I'm just a crazy person. I like having and looking through old tournament books and playing through selected games. I also love looking at cross tables and reading the random remarks about the players and the venue. I also have an enormous set of more job specific books. I have reasonable storage, but it is still finite, so my better half is constantly nagging me about cleaning up and getting rid of the "junk."
Another category of old books that I consider worth owning are the chess materials that were used by the great players themselves. For example:
https://en.chessbase.com/post/bobby-fischer-s-life-for-sale-on-ebay
https://en.chessbase.com/post/sinequefields-purchase-bobby-fischer-s-che-collection
This is why I treasure the older books that my chess coach used to improve with.