Communism was/still is (depends on how you feel about China) a system that billions of people lived through. I think there’s been a great amnesia about this in younger people who’ve never met someone who interacted with Really Existing Socialism
Anywho, my reference to communism not taking off is mostly to the utopian idealogy, I understand many people live/d under communism, but it was really just socialism with some caveats.