I only read 60-80 books a year, maybe 40-60 on a Kindle. I guess I need to take up some sport to live long enough to reach your numbers (and to stop deleting things).
Even including an occasional article, 'thousands' is very impressive.
My worst habits are largely (TT)RPG manuals. I've got a huge collection from DTRPG especially. Sometimes one RPG purchase will have ten/twenty PDF files inside it (player's guides, GM guides, adventures/modules, etc). (Not to mention the combinatorial explosion if you ever talk yourself into a big sales bundle or two.) There's a bunch of weird reasons to keep them around "read" or not, and make them searchable if I need to look something up or am trying to remember a detail. Syncing some of them to my kindles or to other tablet devices from time to time can be handy for portable retrieval (or on the go skimming). I eventually realized my Books folders were huge and unmanageable even with a detailed folder structure and have been happy with moving that all to Calibre with better tags and metadata management.
I'm a horrible hoarder but I've also had a kindle and have been using Calibre since it started. You can store a ridiculous amount (thousands+) of books on a Kindle but as soon as you do that the interface slows to a crawl, it's really unpleasant to use at that point. Just page turning in your library takes seconds and I think it only lists 10-20 books a page.. oof.
I bounce between books a LOT. I don't read daily or anything and no speed reading skills but I'm usually reading 5-10 at a time and I fall asleep to audiobooks.
