Not to mention how much communism fails from an economic standpoint. To read Marx is to read a tribute to the law of supply. Marx has obviously thought this out a lot, and he has decided that diamonds are worth more than shale because diamonds are really hard to find, and that tailor-made suits are more expensive than rags because tailor-made suits take a lot of time and effort to make.
What Marx never picks up on, of course, is the law of demand. People don't give a shit about tungsten necklaces, despite the metal's rarity, and tulip bulbs were the Beanie Babies of seventeenth-century Holland despite requiring absurdly little labor to manufacture. I don't really blame Marx for this mistake - economics was a fledgling science around his time, it's understandable that one could get caught up in thinking that the market was driven only by supply or only by demand... but that people today still make this mistake is inexcuseable.
That one simple mistake led to many incorrect assumptions. For instance - boiling such distinctions as "skilled labor" and "unskilled labor" down to mean a mere different in time required to perform their task. This assumed that you could take any man out of the manufacturing process and, giving him a bit more time, allow him to churn out a finely made coat. It ignored the sevice sector of the econmy entirely - that people will pay based on quality as well as cost. It assumed that a centrally planned economy was not only feasible, but the best way to run the market, a horrendously incorrect assumption. The government wouldn't ignore demand - it just would be too slow to respond to it. And the period in between the time that demand shifts and the government responds is responsible for bleeding the economy dry in wasting resources on the overproduction of a certain good.
Now, that's only one of the fundamental flaws of communism, but listing them all at once would detract from a solid debate.
“It is a strange paradox that today’s central banks are generally staffed by economists, who by and large profess a belief in a theory which says that their jobs are, at the best, unnecessary, and more likely wealth-destroying. Needless to say, this is not a point widely discussed among respectable economists. Nevertheless, it is an issue worth pondering.”
George Cooper, The Origin of Economic Crises