The monetary system does not need to affect societies morals, but it can, particularly when working in conjunction with other forces, such as politics, governmental systems, and advertising.
A perfect example is the ethos 'greed is good'. Is greed actually good?
I would have said 'striving is good, greed is not'. However, when you listen to most people talk, without their admitting it, they believe greed is good (it's all about me - which is what greed is about). Don't get me wrong - there is an argument for greed is good. It's an easy argument to understand. It's a much more difficult argument to understand why it's not good.
That's because 'greed is good' is easily explained on a personal level, short term outlook, and on a very superficial level for society. 'Greed is bad' does not reward the individual (and 'striving is good' sounds like too much hard work), while the affects of greed require a willingness to consider (and be considerate of) society in it's entirety, the flow on effects of greed, and the long term repercussions.
So why do such a large percentage of people believe greed is good? It's not just because of the monetary system.
And materialism too, stems from the 'it's all about me' attitude (and is not so dissimilar to greed).
The real question is, where does the 'it's all about me' attitude stem from?