Greed is not the cause of capitalists’ behavior; it is a quality they acquire in accommodating to and internalizing the requirements of competitive survival within the capitalist system.
The system is a contradiction: the very logic imposed on the capitalist undermines the overall success of the capitalist. For Marxists, no law, rule, regulation, or behavior pattern provides an escape from this contradiction; none ever has.
To achieve a society that exhibits liberty, equality, fraternity and democracy, the object to change first and foremost is production.
Marx effectively argues that a genuine political democracy requires an economic democracy as its ground and partner.
Capitalism is superseded when the workplace relationship designated by the term exploitation ends. That happens when productive laborers no longer deliver the surpluses they produce into the hands of others who appropriate and distribute them and make all the key decisions about those distributions.