Why did Karl Marx believe the state would eventually wither away under communism?

Karl Marx argued that the state functions primarily as a tool for the ruling class to repress lower classes. He believed that after the proletariat overthrows the bourgeoisie and establishes a "dictatorship of the proletariat," the state serves a temporary purpose: to prevent counterrevolution and consolidate power.12

Marx theorized that once the class struggle ends and a classless society is achieved, the fundamental reason for the state's existence—class-based oppression—will vanish. With the disappearance of these class divisions and the removal of the threat from the displaced bourgeoisie, the repressive institutions of the state (such as police, courts, and prisons) will no longer be necessary. Consequently, the state is expected to "wither away," leaving behind a society organized around the principle of distributing goods according to individual needs.12