I am 100% certain that I am the only person in this thread, possibly in this whole board, who has read all of both The Ego and Its Own and The German Ideology, and so I am uniquely qualified to say that you are a fucking dumbass and this comment is wrong wrong wrong. Did you just guess about Marx's critique of Stirner's metaphysical and historical theories? Don't answer that. I know you did.
Marx criticizes Stirner's philosophy by saying that the entirety of it is merely "phrases about phrases". The philosophy only deals with what things are called, and how abstract concepts don't exist in the real world, and assumes that to be the end all be all, without dealing with the real material basis that leads to those abstract concepts becoming used by humans to talk about the world. Stirner lampoons the ideal for being nonexistent, which is technically true, but he ignores the real existence which gives rise to these spectres, instead imagining them as having risen up out of nowhere. Marx says that this is merely another form of idealism, just a more cynical one than the old school type. He believes abstract concepts to be ruling the world, exactly the same belief of the religious that he attempt to criticize. Despite its appearance as revolution, the only thing it changes is the ego’s attitude, and not even its attitude about real things, only its attitude about abstract concepts. The major thesis of his critique is that you cannot change reality just by changing your ideas.
He also criticizes Stirner's attempts to analyze history, pointing out that pretty much everything he says is just wrong.
It doesn't really matter though in the context of this thread though because the German Ideology doesn't really touch on issues of morality or "meaning" or nihilism or anything like that, it just discusses materialism and views on human nature by contemporary german philosophers and does not address whether or not life is worth living or shit like that.