Socialism makes many mistakes in its assumptions. It discards human behaviour. It assumes that humans work in self interest under other setups and therefore exploit other human beings. It assumes that the same human beings will be magically transformed into philanthropists under a socialist setup. A person who exploits under capitalism is bound to be corrupt under socialsim.
Exploitation disappears with competition or is at least brought to a minimum.
It is unfair to compare socialism with good people against capitalism with villains. The same standars must be used to compare the two systems. France under socialism flopped. The same Mitterand who nationalized went in for privatization. Political stability has nothing to do with economy.