If you think that, then you can't have
read much communist literature.
Marx spent large parts of his life criticising the idea that this was easy, and criticising the idea of the "inherent goodness of human nature".
On the contrary, Marxism assumes that it is human nature to first of all satisfy our own basic needs. In the German Ideology, Marx made the point that if a socialist revolution were to happen in an under-developed economy (like say Russia, or China, or Cuba, or North Korea, or Vietnam at the times of their respective "revolutions"), then redistribution would only make want common, and the same class struggles would reassert themselves. It was Lenin who laid the groundwork for ignoring that central part of Marx' of theses - a part he kept repeating in various contexts throughout his life.
Because a vital part of Marxism is the idea that society moves through phases that are dictated by social and economic conditions for production, and which "traps" us all. Marx did not see the capitalist as evil, nor did he see the workers as good - he saw everyone as effectively being forced into roles they either lived up to or lost. E.g. a capitalist that failed to act like a capitalist would go bankrupt and enter the working classes.
It was not "inherent goodness" Marx expected to bring a socialist revolution, but the working classes rising up in anger as capitalisms focus on increased productivity eventually reaches a point where the way of further increasing productivity makes capitalism itself fail as it runs out of fresh markets to expand into, and turns inwards on itself, with wages and jobs eventually being the only thing to cut. Couple this with the expectation that the ruling classes will refuse to yield to popular demand, but instead will use the means of oppression available to them.
The only reason a socialist revolution is considered necessary by Marxists is the assumptions that humans are not "inherently good", or at least not "good enough". But nor are they evil: It is natural to want to keep what you have, and so natural for the ruling classes to resist.
> Produce as much as you can, take as much as you need, what could possibly go wrong?
>
> (Spoiler alert: pretty much everything)
Of course no system has ever attempted that kind of distribution, and Marx explicitly warned (e.g. in Critique of the Gotha Program) that this was a long range goal for an advanced, well developed communist society, and that in the intermediate stages leading up to a socialist revolution, and during socialism, he saw it as more realistic to aim for a gradual transformation of the modes of production and to gradually redistribute through changes to taxation and salaries and welfare systems - not some "free for all" overthrow of all existing structure. In fact this is a defining difference between Marxism and the various anarchist ideologies (which tends to advocate the immediate destruction of the state to various degrees)
Even Leninist and subsequent bastardisations of Marxism kept to this - in large part I suspect because it became a convenient excuse for the various party elites to keep the masses in check while they lived in luxury.