Karl Marx’s prediction was that capitalism would lead to the numbers of wealthy property owners (the bourgeoisie) becoming smaller and smaller, while everyone else sank into an immiserated proletariat, which would eventually revolt to overthrow its masters and introduce a new socialist order. During the century after his death, his analysis was invalidated by two factors that he failed to predict: Where it was successful, capitalist industrialisation created vast new intermediary classes ranging from skilled workers like electricians to middle class professional managers, clerks and engineers. These may not have owned much capital, but they were well paid and certainly did not identify with ordinary unskilled workers. The second factor was that whether because of the needs of war, fear of revolution, feelings of national solidarity, or Christian charity, the capitalists acquiesced (albeit unwillingly) in state programmes to redistribute wealth and ameliorate property through systems of social welfare.
Today, however, a situation is developing in the West that is much closer to Marx’s predictions, though he could not predict the specific reasons.