exploitation and alienation
karl marx argued that as that mean of production become concentrated in the hands of the few, the balance of power between capitalists (bourgeoisie) and laborers (proletariat) tips further in favor of the bourgeoisie. because workers have noting to sell but their labor, said marx, the bourgeoisie is able to exploit them by playing them less than the true value created by their labor. in fact, marx thought, it is only through such exploitation that capitalists are able to make a profit and increase their capital.
and the more capital they accumulate, the more they can exploit worker. marx predicted that eventually worker would revolt. unwilling to be exploited further, they would rise and overthrow their oppressors and set up an economic system that would truly benefit all.