I'm not a professional in these areas, but it seems to me that four things or trends upset the 'balance' and made terrorism a viable option.
One was the fawning press coverage of the MSM to the murders in Munich.
Second was the moral victory that the Egyptians had in the Yom Kippur war. In 1947, 1948, 1956 & 1967 they had the rationalization that the West was activiely supporting their enemy and that is why they last. In 1973 they proved that the Islamic world could fight back & "win". The Egyptian army is still claiming that they weren't defeated (quoted in a History or Military channel TV show) because they "stopped the Israeli army from entering Cairo". This was the first strategic Islamic victory since the conquest of the Balkans.
Third was the Feminist movement in the Western world. Prior to that time, the stereotypical Western family could be viewed as not much different than the Islamic model. The woman stayed at home and raised children. When the Western model changed to 'liberated women', this export became a challenge to the Islamics.
Fourth was our retreat from Vietnam. Not only could the West's client state be beaten, the "Great Satan" was run out of town by the peasants.
I like these, and can agree with all but #2: if you believe (as I do) that suicide bombings are driven by the "honor/shame" paradigm, then "winning" in 1973 should have brought honor, not more desperation and shame.