By what metric?

The Lindy effect is concerned with survival, which is affected to a large degree by, in this case, memetic fitness, which these books have in spades.

By the quality of the book.

I believe K&R is a wonderful introduction to C - "wonderful" as in "let's open the editor and try this". It's well written, simple, and you are left with the feeling that someone just gave you a Jedi weapon.

It took a while for us as a community to realize that such a Jedi weapon can easily slice your fingers off, because before the internet the worst that would happen is "it crashed again" but that was kind of normal.

I love that someone has this take, but I think you should elaborate. In what sense are they terrible? Why do they experience sustained popularity? What does this tell us about Lindy?

That people confuse Lindyness with quality.

K&R 2nd edition is an excellent book, not just as a historical artefact, but as actual literature (not joking, it's very entertaining to read).