We don't necessarily need money, but we do have specific human needs. In today's modern countries, we provide for those needs with money. These needs are safety, food/water, and shelter.
If you could provide these needs without money, you wouldn't need it. In fact, there are many places in this world where they do not have currency. But, they still provide these needs.
Now, referring to our society - after the basic needs, our need for money is really an individual answer. The first step every person needs to do is look at their life and decide what truly makes them happy. Write out these specifics. Does a Mercedes really make you happy? Or does an annual vacation make you happy? Does quality time with your family make you happy? Go down the list and write it out.
Once you know what makes you happy, you can write a dollar amount next to it. A Mercedes will have a high one, a vacation can be cheap or extravagant (your choice), quality time may have a $0 next to it because it can be accomplished for free.
Now you know how much money you actually need. And now you have a purpose for pursuing money.
Too many of us pursue money without purpose. They are trying to get more money, but don't know why. And when they look back, they realize they worked for some things that didn't really make them happy. And, at the same time, neglected things that could have been achieved without money
RE: Why do we have money?