Of course this is what we all learned in basic economics, but the reality is that it isn't that simple. Take China for example, a very lucrative market with increasing technological advancements. Some might argue China is not really a communist state but it is *technically* communist based on the idea of democratic centralism, which was an idea presented by Vladimir Lenin, which allows for open discussion of policy. Many people consider China to be in the early stages of socialism though. Also, OP said that humanity is too greedy for communism to work but the truth is that single people are too greedy for it to work. Sounds great as a whole society but it takes just one corrupt government official to fuck it all up.(most) People want what's best for them not everyone else.