The purpose of communism has never been that of being "economically successful".
If you want to dismiss communism as a failure, first off, you should not measure money, and not even wealth, but simply happiness. Second, you should measure equality, and, finally, you should measure the happiness of the least happy, not that of the most happy.
1. The doctrine those states called "Marxism" or "Marxism-Something" very much emphasized well-being as material well-being stemming from economic success.
2. Self called Socialist states, generally referred to as Communist states as they were dominated by an all powerful "communist" party, have not been in general successful in terms of general happiness, although they argued that they at least brought an industrialized level of economic prosperity whereas capitalism would have left those places stranded in misery. Wether that is true or it was worth the price is a question for historians to debate on.
To summarize : Humans don't live by bread alone, and I am not even sure the bread was great there.