Greed and the danger related to greed is an ancient well-known problem. The ancient Greek wrote about it and it’s also an important issue in the Bible.
In recent history of humankind for the last 500 years banking was as important for progress as was science and technology. The problem began with the creation of speculative bubbles, because greed all of a sudden had a very powerful boosting mechanism. These bubbles have existed for hundreds of years. The invention of derivatives and especially credit derivatives turned this booster into a three-stage rocket for which even the sky wasn’t the limit.
Investment banking can be a good thing. How can we build Desertec in the Sahara replacing fossil fuels with solar power for the whole of Europe? Not by shooting all the bankers. Venture capitalism can be a good thing too. How else could Google have bought there first farm of servers to index the web and allow fast searches with relevance ranking. How else can new ideas that require capital have a chance?
The problem is banking for the sake of banking. Leverage can become a dangerous thing. It makes greedy people more greedy. This is what happened at Lehman Brothers. Therefore we need moral and ethics, but also better regulation world-wide including all the off-shore havens. There’s a lot of good research, see for example
http://en.wikipedia.org/wiki/Niall_Ferguson
I can recommend his book.
http://en.wikipedia.org/wiki/The_Ascent_of_Money:_A_Financial_History_of_the_World