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"
A great segment of an intereview of Milton Friedman by Phil Donohue. Phil looks like a deer in the headlights.
“Is there some society you know that doesn’t run on greed!?”
http://www.thelibertypapers.org/2007/10/30/milton-friedman-vs-phil-donohue/