Anger creates tension. Normal people, as you said, release this energy is sex, sports, rock 'n' roll. Moslems release their built-up anger in mass murder.
Now this plot, just like 9/11, required a great deal of planning, intelligence, creativity, dedication, talent, and teamwork. Normal people with all these talents put them to use putting a man on the moon, building a space shuttle, performing brain surgery, finding a cure for cancer, inventing the personal computer, composing symphonies and works of art.
Look at what the Germans and Japanese accomplished once they were convinced to abandon their warlike ways and apply their talents to creative and productive goals.