Marxist theory was built by bourgeois thinkers studying bourgeoisies, not proletarians

Evidence

Marx, Engels, Lenin, and Trotsky were bourgeois ideologists in terms of their social origins and educations. Marx and Engels had seemingly acknowledged this in The Communist Manifesto: “[S]o now a portion of the bourgeoisie goes over to the proletariat, and in particular, a portion of the bourgeois ideologists, who have raised themselves to the level of comprehending theoretically the historical movement as a whole.” Furthermore, with the exception of Engels, none of them seems to have given over much time to the study of working classes. For the most part their works were concentrated on the bourgeoisies: their histories, their States and administrations, their organization of production, their ideologies and philosophies. All, of course, certainly looked closely at the historical and social processes of the breakdown of societies, viz. revolutions, but these were the contradictions of bourgeois societies. It was also the case that few proletarian intellectuals were ever attended to in their writings. This raises again the question: Is Marxism a theory for the proletariat or of the proletariat? — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 2432

Categorization

• DEFINE: Sharpens the definitional boundary of what the ‘Black radical tradition’ opposes: a theory authored by and about the bourgeoisie rather than generated from proletarian life.