I'm going to slightly rearrange your post Sunstone so I can answer it better.
For the purposes of this thread, let us define "greed" as wanting more of something than you need to live a decent, dignified life.
At some level you are going to have to make a distinction between "want" and "need" to define what is legitimate and illegitimate desire. Most probably, it would mean treating "need" as somehow objective of the individuals desires and "want" as subjective product of an individual desire. If we were to take a very literal definition of "need" as physiological and biological, it would be the bare minimum necessary for existence. That is clearly not you mean here.
"Wanting more of something than you need to live a decent, dignified life" is using need in a way that is subjectively very loaded by how you define the "decency" of life and the "dignity" of a person. There is no wholly objective way to do so, and there will be an interaction between the definition of want and need that will be relative to a range of historical and cultural factors.
The importance of the definition is that it is presenting a moral argument for regulating human behaviour based on what is considered a legitimate or illegitimate desire. Whilst it can be read as an abstract principle, anyone tasked with enforcing that kind of norm of behaviour is going to have to make some subjective distinctions which will often not be very clear and could be extremely arbitrary.
Some years ago, an international survey found that most of the people surveyed in over 100 countries were not all that greedy. When asked how much money they needed to be happy, the majority reported they wanted enough money to cover their living expenses and a few luxuries (such as vacations) plus a reserve for emergencies.
Historically speaking, most people in developed countries now live like Kings. We have washing machines, dish washers, TVs, smart phones and internet access. These are wonders undreamed of to most medieval despots with the wealth of a whole nation at their disposal. Maybe we don't live in the palace of Versailles, but if you have a Chinese takeaway, you're eating food that would have been available to Chinese emperors. So again, "need" is a highly relative and subjective concept, particularly when it is about "how much money they needed to be happy".
That "something" could be money, but it could also be nearly anything -- from toys and food to power. And let us define "unbridled" greed as greed that is not regulated, checked, or controlled.
The problem is that the conception of "unbridled" greed contains within itself the
definition of something which should be "regulated, checked or controlled". It doesn't explain
why such controls should exist in the first place, merely that they are in a form of circular reasoning.
Money has a particular attraction for "greed" however. And there is an argument to be made that money is a substitute for social relations instead of the naked exercise of power. By exchanging one value for another voluntarily, it resolves social conflicts and the competition over resources without resorting to open violence. Greed for money is therefore comparatively benign compared to the desire to have direct power over others based on the exercise of violence.
With concentrations of wealth come concentrations of political power so that great disparities in wealth lead to great disparities in political power. Thus, we can ask whether some few people should hold all or nearly all the political power in a society while the vast majority of people hold little or none of the power? Historically, great disparities of wealth have led to oligarchies and then tyrannies.
The relationship between Capitalism and Freedom is much more complex that simply saying "free markets lead to free societies" but it is still largely true. There have been mixed economies (often described as "socialist") that have been democratic and many free market economies that have been dictatorial, such as Pinochet in Chile or General Park in South Korea.
However, there clearly is a relationship between the centralisation of economic power and political power in a planned economy. The road from Oligarchy to Tyranny is often far longer than the road from Socialism to Tyranny. Oligarchy is at least a corruption of free institutions and they still "exist" but not in a functional way, so there is more opportunity to save them. These are large historical processes that are often not entirely within the power of the people to determine, nor can the state entirely control the corruption of a society and its ideals.
To live in a "planned" society greatly reduces the scope of individual autonomy because people have to work in harmony the plan. There cannot be independent activity of the state. In such a society, there is no longer a clear distinction between "public" and "private" spheres of activity. the
private sphere has an economic basis of private property. Capitalism therefore creates the economic basis for a civil society based on institutions independent from the state, such as a free press, trade unions, or political parties.
If the means of production are owned by the state, it means that the printing press and television stations are state owned. Trade unions cannot operate freely because having the right to strike means sabotaging the plan. Economic planning must necessarily be undertaken by people and historically it has therefore always been centralised. The monopolisation of economic power creates the economic basis for a monopolisation of political power in a one-party system. opposition to centralised planning, its methods and objectives is no longer opposition but is counter-revolutionary activity.
Overall, therefore free market dictatorships are "less" absolute and "less" totalitarian than planned economies. Nazi Germany was capitalist and was arguably
less dictatorial than the Soviet Union because it has competing agencies to achieve the same goal. It retained some elements of an independent civil society. The Soviets however- having had a revolution to sweep away private property as a basis for "independent" institutions- did not have this "problem". This doesn't mean that the victims of dictatorships cease to be victims, but from a wider historical perspective a capitalist dictatorship is often "freer" than a socialist dictatorship at an individual level.
People still die though and you could well make the argument that the fact the Nazis had such a multilayered and chaotic power structure built on competition was a direct contributing factor to how irrational they were. The Soviets were comparatively more rational as dictatorships go and in some ways more frightening for it. The Nazis belief in inequality meant only certain groups were targeted for extermination. Under the Soviets, you don't need gas chambers. Under Communism, everyone is equally entitled for extermination, including the party faithful, is they fall under suspicion.
People who use good intentions to seek to change the very essence of a person rather than treat it as private property, make more vicious dictators than people who simply corrupt. bullies and thugs will at least leave you alone when they get tired and bored of beating the crap out of you. But moral perfectionists have the sadism to want
everything you are to be made in their image. There's no easy way to chose between two varieties of tyranny, but being the victim of a corrupt tyrant is slightly lesser evil than being the victim of a fanatical one.
It is sometimes said that if the wealth of the world were more evenly distributed, no one would starve. Whether that's true or not, it is obvious that if the wealth of the world were more evenly distributed, fewer people would starve. Sadly, the world's wealth isn't evenly distributed for some people cling to fortunes vastly greater than anything they need. Perhaps as a consequence, a person dies of starvation somewhere in the world every ten seconds, or over 8600 people a day.
The principle of an equitable distribution of food here deals directly with subsistence. As a principle, it therefore fairly accurately reflects a biological constant and is something that- outside of psychopaths- none of us would want to deny if we were faced with watching other people starve to death.
However, the idea of someone deciding how to distribute food is only attractive because we are talking about an "abundance" of food. In creating a permanent political position by which someone would distribute food as a substitute for market exchanges however, we would be much less comfortable with someone exercising that power in deciding how to deal food shortages. Who gets the food becomes a political calculation based on how "useful" someone is for society. In the Soviet Union, following the bad harvests after collectivisation, a political calculation was made that food should go to the working class helping industrialisation rather than the Ukrainian peasants who were thought guilty of sabotaging socialism by undermining collectivisation. The latter were deemed "enemies of the people" and so the whole geographical area of Ukraine was denied food in a genocide known as the holomodor.
The Soviets made a superficially rational decision about what was in the public interest. However, given that death is inevitable, if you give the state to means of determining who lives and who dies whether that be control of the food supply or through mass executions, you reduce human beings to "when" they are killed not "if". Individuality becomes irrelevant and the moral values that we live by are replaced by expediency.
I'd like to live in a world where everyone has enough food and parents don't have to watch their children die. But I have yet to hear an argument that intentionally deciding who will starve is morally superior to "leaving it to the market" to make me feel at ease with someone exercising that kind of power to distribute food for political reasons. Power corrupts, not because we're evil, but because it strips away our illusions to reveal how vulnerable we are and the futility of our earthly ambitions. we may have achieved the capacity to realise the totalitarian ambition to save the world, but we forget anyone who can save the world also has the power to destroy it. There is so much ego involved in wanting to determine the fate of mankind. I don't think we have yet reached a stage where we have come to appreciate our shared vulnerability to exercise that power wisely, if we ever could.
Is unbridled greed good for a society or for the world?
Self-interest has typically produced better results than systems built on negating it and turning "good deeds" into an obligation. The reason why we believe helping others is good is because it feels good. So ultimately, helping others is partly selfish. unbridled greed at least has the (admittedly unintended) benefit of letting the rest of us decide whether we want to be nice to each other.
As far as evil goes, it is slightly more human than a masochistic morality where good intentions are the excuse we use for our cruelty to one another. It is better to accept our imperfections as part of who we are than to sacrifice people for our ideals. we should not make it our business to look into men's souls based on absolute standards of good and perfections unless we are willing and prepared for others to search our own and find us wanting.