"Marxism is the delusion that one can run society purely on altruism and collectivism"
That might be true of communism,but, in fact, marxism is even more ludicrous. It posits a crazy pseudo-hegelian philosophy that leads to iron-cast historical "laws" that societies follow neatly and allows itself the conceit that it is scientific. Amusingly Marx and his followers never had anything much to say about how a socialist society would orshould be run. It is truely a worthless ideology.
Yes, Marx boasted that he took the absolute idealism of
Hegel's "world spirit" and "set it right side up", that
is,into the dialectic of history based on materialism.
This dialectic was, as you indicate, designated to be an
inexorable "law of history". The supreme irony is that
despite the fallacy of this whole system -- Marx did have
certain insights, one of which was that capitalism was a
"progressive" force historically, though its time was
passed.