"Greed, for lack of a better word, is good. Greed is right. Greed works. Greed clarifies, cuts through, and captures the essence of the evolutionary spirit. Greed, in all of its forms, greed for life, for money, for love, knowledge — has marked the upward surge of mankind ... "
Most of human progress can be traced to people who were not satisfied with their lot, and wanted better
The destructive emotion is "envy", unhappiness caused by knowing your neighbor has more than you, coupled with the desire to drag your neighbor down to your level rather than advancing yourself to his.
The most destructive attitude is saying to yourself "Nobody but ME should be allowed to have anything good"