Maybe i'm wrong, but isn't GirlFriday's argument the opposite of what she's trying to make? Mother Therasa knew that money could corrupt, that's why she left it? If she knew that it wouldn't, why wouldn't she had kept the money and used it philanthropically.
Oprah Winfrey is a good example, but she is definitely the exception. If your prof/teacher is asking for a macro view of things, then you'll need something more.
However, here's my argument: Individually, it does affect our morality. We become more self-centered and egotistical as we acquire more material wealth... we acquire the Armani suit to define who we are (i am affluent), but that Armani suit is not enough, so we need the porche. The porche becomes dated in a couple of years, so then we need the next best thing, which might be the new Lexus, etc, etc. It snowballs and we simply become more materialistic. We soon equate happiness with material possessions. We remembered how it felt when we got that first porche and drove it on the road, the looks and ooo's we got from other people. And we try to recapture that with future possessions, believing there is 'THE' item out there that will make us completely happy. There is no such thing of course, the guy from poverty looks ahead and believes that making $50k a yr and owning a house is heaven... but once he has that he looks forward again, believing that making $200k and having a house and 2 beemers is heaven. It doens't end there either.. once he has that he looks forward again and believes that making $500k and having a woman 20 yrs younger then him will make him happy, etc, etc, etc.
The suicide rates amongst the uppermiddle class to rich is HIGHER then the suicide rates amongst the lowermiddleclass to poor. The psychological disorders such as depression and personality disorder is also much higher amongst the upperclass then lowerclass.
Now, that's my argument for individuals. As a society, it appears commercialism is making us MORE moral. Let me see if i can argue it.
If you look at society past, you'll notice that it was worst off. There was slavery in the past, women didn't get to vote, laws/justice were more bias or lenient (rape, child abuse, etc), and even behaviors such as smoking was considered acceptable (today it's not illegal, but definitely frown upon). Then, as our economy got better, so did our sense of justice and morality. Slavery was abolished (not just abolished, but an entire civil war was fought over it), women got to vote, prejudicism becomes a no-no, etc, etc. Why is that? I would say that as we become more materially successful, we want to maintain that success (and happiness). We have a good economy, and we want that economy to continue being good... but we also want to spread the good. It's just like a happy drunk in a bar, he's more likely to buy everybody a round of drinks then the drunk in the bar that's pissed. This also makes his time more enjoyable, and we do the same thing as a society. We like our standard of living, and we know if we make another society standard of living better, that our's would be enhanced as well (ie, if Mexico's society becomes better, so will ours).
I think as human beings, when we're not happy, we become very selfish (as a whole i mean... there are LOTS of exceptions). But when we are happy, we tend to also become very good and benevolent. Here's an example: At the end of the 80s, after Reagan dumped all those trillions into the economy trying to build Star Wars and what not, and with all the conglomerate corporate mergers, and the economy jsut being damn fine, the world rushed into the middle east to save Kuwait. Then, in the early 90s, when the depression set it, Bosnia had their own war, with a pretty damn good chance of disrupting the European society and starting a serious war, everybody was hesistant to get involved, including the Europeans!
So if we're happy, we're nice... currently, we believe that material goods make us happy, so if our economy is good and we have lots of money, then we're happy and nice. But like my argument on individuals shows, material goods doesn't really make us happy... we only believe it does. And even then, it's not permament happiness... look at all the rich, you'll think they were the happiest ppl in the world, running around naked and having huge orgies (i think it's only the German aristocrats that does that).
So MY thesis would be: Individually, material goods makes us selfish... but as a society, material goods have a macro effect of making us nicer. The proof is in history... and also the world over (especially in developing nations). Look at China. 20 yrs ago they were much worst then today... despite all the western media that says they're evil and the chinese are unhappy with the government, the chinese ppl are quite happy and quite content with the government... there could definitely be changes, but they realize the government will make changes, and they realize the change will come when the economy is better and the standard of living is higher.
There ya go... i doubt that helped you, probably made you more confused... and not like i have any substantial evidence.
Anyways, those are my ideas. Hope it hasn't confused you.