Communism is a utopian ideology that inherently fails and is tyrannical. It inherently fails and is tyrannical because it entails government ownership of the means of production, and therefore violates liberty by eroding or abolishing all private property rights, all private ownership of the means of production. It tries to centrally plan much or all of an economy, which inherently leads to chaos and problems because it cannot calculate economically - it cannot read the minds of the consumer, it cannot determine demand like a consumer. As a result, it cannot properly allocate resources. It has no profit/loss margin, meaning that it has no incentive to be efficient towards the consumer's demand.
It leaves little to no incentive for the individual in society to increase their own well-being, and as a result there is no real economic ladder for people to climb up. Ideologically, communism is based on an absurdity - that each person, the whole, owns an equal quotal share of the person and property everyone else. This is a pure utopian impossibility, it is not logically or physically possible.
The real result of communism is where an oligarchy or dictatorship, a group of central planners, owns the person and property of the individual and people in society IN THE NAME of communal ownership or "equality". The results of communism is a true lack of standard of living and a significant loss of liberty. A communist system cannot finish all stages of production and therefore can only yield half-produced capital goods.
Collectivism is dangerous. Communism fails precisely BECAUSE it is a flawed concept. It is entirely ignorant as to how people work. It promises an impossible utopia that "cures" human nature. It is hostile to individual rights because it holds the utopian goal of "the whole" above the individual's rights. It violates the individual's rights in the name of upholding a fictious construct of the collective's "needs".
It stifles individual potential in the name of creating a utopia of pure equality, as if it can stop human beings from being self-interested and as if pure equality in life would be desirable. If you do not have private ownership of the means of your production, then you are a slave. You are barred from increaseing your own well-being in the name of "the collective" - you have no property rights, you are not the owner of your production.
All of socialism's defendants have to present is egalitarianism, where they are argue for well-meaning goals that they alleged aren't met in capitalism. The true capitalist doesn't argue that those egalitarian goals are possible at all to begin with, they point out that they are not achievable because human beings exist - and we question if those well-meaning goals are actually "good", if they actually would be desirable if they were realizable.
But they aren't realizable to begin with. You aren't going to end gaps all between wealth, and there is nothing inherently wrong with gaps between wealth when that wealth has been persued under the voluntary economic means. By the very nature of human beings and the diversity between individuals, you will never have pure equality. Regaurdless, all the socialist has to present is egalitarian goals that do not stand up to scientific scrutiny.
Capitalism makes no pie is the sky promises to people of perfect equality and collective ownership - it is what happens naturally as a result of the free decisions that the consumers, producers, employers and employees in society make. Many on the left fail to understand that socialism, government ownership of the means of production, takes away the freedom of economic choice in the people.
Capitalism is a "consumer democracy" - you vote with what you choose to buy, sell, trade and invest in. Socialism inherently disrupts this freedom in economic choice by having central planners arbitarily decide, with no incentive toward the consumer's demand, no profit/loss margins. There is no economic ladder to ascend because the individual is denied the incentive and oppurtunity to improve their own economic-wellbeing beyond the whims of the central planners. Therefore, your standard of living is centrally planned and you cannot improve it beyond that point.
At such a point it is the mere whim of men in an ivory tower as to what your job is, how much you make, how long you work, what price you have to pay for everything. The whims and utopias of central planners always fail - only the people's own decisions can accurately produce and accumulate a standard of living. The central planners cannot create well-being and prosperity the way that the individual's own free choices can. They do not serve as a legitimate substitute for the choices and actions of the individual. Capitalism merely asserts that you cannot achieve the pie in the sky goals of socialism and it proposes no magical "solution" to inequality (diversity!) because it knows that there is none.
It also must be realized that Marx viewed socialism as the "transition" period to his communist utopia - and Marx's utopia required "withering away at the state". In short, the anarchist branch of communism viewed big socialist government as a means for transition to their anarcho-communist utopia of collective ownership. The means by which the socialist transition is supposed to take place with is the socialization or collectivization of the means of production. In the communist utopia, the means of production is supposed to be 100% collectively owned and everything 100% equal. Presumably, for the anarchist communists, once all private ownership of property was abolished and turned into collective ownership, the state would wither away and not be necesssary.
Of course, because of the logical and physical fact that 100% equal collective ownership of property is an absurdity, communism never truly reaches a pure pinnacle of collective ownership or equality. It degenerates into a board of central planners that own the person and property of the citezens IN THE NAME of collective ownership and equality. A dictatorship or oligarchy. It never results in what Marx himself would have desired, nor the anarcho-communists.
As Ludwig Von Mises notes in his classic book "Socialism":
"Any advocate of socialistic measures is looked upon as the friend of the Good, the Noble, and the Moral, as a disinterested pioneer of necessary reforms, in short, as a man who unselfishly serves his own people and all humanity, and above all as a zealous and courageous seeker after truth. But let anyone measure Socialism by the standards of scientific reasoning, and he at once becomes a champion of the evil principle, a mercenary serving the egotistical interests of a class, a menace to the welfare of the community, an ignoramus outside the pale. For the most curious thing about this way of thinking is that it regards the question, whether Socialism or Capitalism will better serve the public welfare, as settled in advance—to the effect, naturally, that Socialism is considered as good and Capitalism as evil—whereas in fact of course only by a scientific inquiry could the matter be decided. The results of economic investigations are met, not with arguments, but with that "moral pathos," which we find in the invitation to the Eisenach Congress in 1872 and on which Socialists and Etatists always fall back, because they can find no answer to the criticism to which science subjects their doctrines."