Again, it isn't that "There are no altruistic people"--- That is not the issue at all. There are indeed plenty of altruistic people. Many individual people may well be able to engage in genuine communism. The problem, is that you cant pick and choose who lives in the society and who does not. A society is made up of the full spread of the human condition.
Therefor, the issue becomes "Are there sufficiently more altruistic humans in the natural distribution to sustain a communist state?"
As far as I can determine, the latter answer is "no".
Without a strong positive bias in the natural mean, the society will not be able to perpetuate itself, and will not be possible.
Is it not the case rather than the state of competitive accumalation, poverty and class conflict in capitalist societies essentially enforces selfish logics on people who in the normal scheme of things?
People have a job as a trader in the market. It is their job to be selfish and make as much of a profit as possible but then as soon as they have the freedom those same people give the money away to charities.
The assumption of selfish human nature rather disregards the degree to which selfishness is enforced in capitalist society through the need to "get a job" and "earn a living".
Basically, for communism to work, altruism must be the rule, not the exception. It is currently the other way around-- As such, it is simply unrealistic to expect true communism to work with the human race as it currently exists.
This does not mean I advocate just throwing in the towel though-- I am a rational human being, or at least, believe myself to be. As such, I see the clearly deleterious effects of the alternatives to true communism, and openly lament that the current status quo is what it is.
The problem yes is the process. People are conditioned to behave selfishly in a certain way by a combination of propoganda, carrot and stick.
How do we go from a state where people work under coercion of poverty/starvation if they do not work in order to selfishly work to acquire wealth from everyone else to a state where everyone does whatever needs doing in return for enjoying an equal share of the total wealth? Dwarf Fortress rather well represents that ideal state and it works because everyone works altruistically for free and recieves everything for free.
One insight I thought of is at the moment because money = power, influence, opportunity we essentially encourage the propogation of the basic values of selfishness throughout society, though it may not seem so obvious given that much of this selfishness is tinged with altruism (I will screw everyone over, so I will get rich, so I can give to orphans).
Perhaps the lack of material incentives to career advancement would weed out such people leading to a situation where the elite consist of those who are most altruistic, thus propogating their basic model of public service as the aim for the ambitions of the population.