Er...when do economists say that greed is a good thing? In fact it is a Deadly Sin (oh Brad Pitt

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But you could not live in a world without money. Would you like to sketch out an idea of how this world would work?
The way that society has developed and the change of people's wants is what makes money integral to everyday activities. You don't, however, have to be greedy. Money is not equal to greed. That is entirely up to you.
Now, there is also Nothing Wrong with having a lot of money. The problem arises if the way in which you have come by this money is not entirely fair. And even Fair Trade coffee is not entirely fair. Therefore there are many implications in the use and acquisition of money which give it a bad reputation. If money was a reflection of your abilities to contribute to the economy, it would be a very efficient means of allocating purchasing power. However, it is not, as it is closely linked to wealth and all this other stuff.
Money by itself is just a medium of exchange and valuation. These bits of paper do not reflect their value in cost of production! Therefore it is how we *use* this money that causes the problems.