In my opinion, Marx wrote his conclusion first, then cherry picked the points in history that supported his conclusion.
I can’t fathom the arrogance of people who say “Marx just didn’t think of x, y or z”. He invariably did, and a quote is easily found to prove them wrong. Yet they continue to say this bollocks. “Marx didn’t consider human nature, Marx didn’t know about x obscure economic theory,” on and on until the cows come home. Capital has 3 volumes, and each is thick and heavy enough to make a decent murder weapon. They are so long precisely because he did do the thinking you accuse him of not doing.
The one single thing we can legitimately say he didn’t anticipate was the computer revolution, and it in fact only strengthens his theories, as digital technology has gone on to strengthen the hold of capital, and laid bare its incestuous relationship with the State.