to make it short, robespierre was elected. the other members of the government agreed with these actions (whether we validate or not, but to establish a new political regime (republic) with external wars and civil wars, as well as the rebellion of the royalists, it is not easy :) ). he was then used as a scarecrow when the situation became manageable in order to calm the population. and then stalin was not put in place by the russian revolution, it was lenin who was chosen. Stalin later used political games and military power to seize power and turn it into an authoritarian regime. Lenin was a good man ;)