[So basically he thought that socialism would work if only the right people were running it. ]
I think a lot of communists thought the system would involve the popular vote rather than what it turned out to be - kings with the title of General Secretary or Party Chairman, along with aristocrats, the nomenklatura, with the title of commissar or secretary of this or that. They were wrong. Communism not only turned out to be a semi-hereditary monarchy complete with aristocracy - it was far more repressive than the monarchies it replaced. While repression can keep a lid on things for a while, it can equally distort reality until a blow-off event occurs, upon which all bets are off. The Soviet bloc could have have kept its repressive regimen for a while, but the further it clamped down, the harsher the blowback would have been. In a way, the place isn’t completely de-communized partly because the kind of large-scale killings of dissidents to which dying regimes are prone did not occur there.