I met the founder of a company who claimed they at one point owned every 3 letter .com domain they could get their hands on. Claims they had around 5000 of them (17576 total), and about a 100 2 letter domains. They had trouble figuring out what to do with them so they let them expire.

After working with them for a few years I believe this story, and especially the part they weren’t competent enough to know what they really had at the time.