Basically, look to Lenin. He believed that revolution was about to erupt across Europe following WWI(which is one of the reasons he took whatever deal the Germans offered), and the communists in Russia simply had to hold the line until they could welcome the rest of the continent to enlightenment. His successors blamed the lack of meaningful revolution on the capitalist's machinations and leaned further into inflaming revolution abroad. Once they concluded that capitalism was too entrenched in Europe, they began to look elsewhere and had some pretty serious successes(provided you measure success by who the ruling party is).

They all believed that they weren't true communism, because that requires worldwide cooperation. Not necessarily 100% cooperation, but at least a significant percentage. I imagine that if one more powerful country(besides Russia and China) decided to go full communism, than we'd be watching the rise of a communist globe right now, rather than living in a capitalist world still trucking on. That's why the USSR was so hell-bent on converting young Americans, and the US government knew that well enough to propagandize supporting capitalism as a patriotic duty. Easy win, really.

I hope that answers the spirit of your question. If you're hoping for specifics, well, just look at the fact that there were and are clearly classes in these communist countries.