Hmm... "Discuss your views critically." Sounds like you want us to do the work for you. I went through theatre training and I focused on the spot that Lady MacBeth has on her hands. I agree that they lost more than they gained, but they were both a little crazy to begin with. So to them they thought they gained the world because they had such a twisted sense of everything after they plotted and schemed, but to the reader you feel they are losers because they destroyed their own lives.
It's the same as criminals. I don't think murderers are born with the wiring in their head to murder, perhaps they just hate someone/thing so much they need to rid themselves of it. Before you know it they become so obsessed with something that they start to rationalize irrational behavior, etc. That's why in so many crime shows you see the criminal trying to explain why they did was ok. But that's a little besides the point.
MacBeth and his wife had everything you could ever imagine, but she goes and screws it all up. Kind of like Adam and Eve. Can you use Adam and Eve as an example? The entire beginning of Genesis counts as a source since it's a written and published book... Even if you don't agree with the Bible, it's still a story that can be used.
