^We need money to have a currency,
to be able to trade our things to others' things we can't produce ourselves efficiently,
for a common known value for items so you can for example sell a house for a lot of money you are able to gradually spend on goods, instead of having to trade it to just a huge amount of someone's household items, food and such.
So that people will have competition so that everyone works harder in attempt to get more things to boost their social status (it's part of human nature to strive for this, communism just does not work) to have a better chance of getting as healthy mate as possible to reproduce with so that their children would be succesful in life and be able to repeat the process with less effort than you had to.

We need money for the society to work. It's not the money that causes problems, it's the people who want it so much that they end up doing anything for it.