Just a simple point I’d like to make so that I don’t forget it:
If you believe that a society has achieved even a moment of socialism, it doesn’t make sense to believe that all socialism is doomed to return to capitalism. If a country can move in the direction of socialism once, it can move in that direction again; and even once it has already moved some distance in a socialist direction, it can continue moving in a socialist direction.
In practice this has been proved by China’s cultural revolution. I guess what I’m saying is that for those who are skeptical, there is ample theoretical reason to believe that cultural revolution is possible.