but I was faced with the consequence of 30 years of book hoarding when you buy at least once a week and sometimes more, and I finally got rid of about 60% of the books or so while moving. Some went to friends and relatives, a few more desirable ones I sold (booksellers are notoriously picky here) and most were given away (90% of the children or YA stuff like the complete Jules Vernes collection I gave to the school where my brother teaches).
Translations I no longer read at all went first (excluding of a few things no longer available in the original language, like a few novels by Frank Herbert), then novels I didn't like and novels I'm confident I will never reread (that includes most Fantasy), then everything in the public domain for which I didn't own a critical or otherwise special edition (like a Rabelais edition with the text established straight on the last published edition while he was alive and such) and that I could replace for free as ebooks (that means dozens and dozens of Zola, Dumas, Hugo, Balzac, Flaubert and other French classics, and other Dickens, Austin and company - many bookcases worth of them). A ton of old paperbacks went because I also owned an omnibus of the complete works.
I decided I'd keep mostly non-fiction from now on (I got rid of less than 50 of those, all big let downs or completely outdated, like political essays published in the heat of things, decades ago...). For fiction everything that's "entertainment" that I'll most likely read once will have to be available as ebooks or I'll pass, and I'll be more choosy with my purchases of literature "to keep", favoring ebooks when possible or else space saving Pléiade and other omnibuses and their US/UK equivalents.
I used to love the idea of owning 10,000 books and over, but after a major roof leak I grew totally annoyed with moving bookcases worth of heavy books out of harm's way (damn hardcovers for this), boxing them, moving the boxes around and that gave me the motivation to do what I'd thought totally inconceivable before (ie: get rid of any book). As for ebooks, I was unenthusiastic and I resisted at first, but I got used to the Kobo after a while and in the end I find it very practical, not to mention the huge amount of money in books it already saved me (the device paid itself in money saved in less than 2 months).