The simplest answer is that Communism was doomed from the start. As a system, there is little to no incentive for the individual to excel, and often there’s incentive to do the absolute minimum required not to go to the camps. In the Communist system people were promoted not because they actually did well, but because they seemed to do well. You can move your way through a lot of things when talking to people who don’t know what you’re talking about. Eventually the corruption, all the weight of ineptitude, coupled with military expenditures that they just couldn’t afford brought the whole system crashing to the ground. It was only after Communism failed so spectacularily that we began to discover just how utterly horrifying it is to live under Communist rule. (hint: look up “Holodomor”)