I always remember this sentence from the intro to vol 1 by Mandel: "The need to answer a sharp and slanderous attack by a German political opponent, a certain Herr Vogt, cost Marx nearly half a year's delay in the production of Capital Volume 1."

He was literally a 19th century redditor.

I find it wild there’s like 3 books of Marx that Lenin never got a chance to read (this, Grundisse and the 1844 manuscripts).

Most of it didn't, lol. Half of what we know of Marx are what he wrote for himself.