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

In Marxism, Karl Marx argued that the state functions primarily as a tool for the ruling class to repress lower classes.1

Following a revolution, the proletariat would establish a "dictatorship of the proletariat" to seize the means of production and prevent a counterrevolution by the displaced bourgeoisie. Marx believed that the state’s existence is tied to these class antagonisms; therefore, once the class struggle is resolved and a classless society is achieved, the state would lose its purpose as a repressive institution. With the disappearance of class distinctions, the state would naturally "wither away," leaving behind a society organized without the need for traditional state power.21

While Marx theorized this transition, history has shown that regimes claiming to follow these doctrines often failed to relinquish power, instead becoming highly centralized and oppressive states.3