But the terrorists'goals seems to be revenge rather than social change. Revenge is very unsophisticated response to injustice. There is no true justice for past wrongs, only more injustice. Two wrongs don't usually make a right.
Many terrorists would claim to be Robin Hood types, for the people and against corrupt governments. But their methods, especially bombs, often randomly kill a wide spectrum of uninvolved people and create fear in society in general. Meanwhile, the targeted government agencies seem to gain in status and importance. The main result is exactly what terrorists claim to be opposing - more restrictions, less privacy and freedom.
It seems what they really want is escalation of the conflict. I think the deeper goal is excitement, the adrenalin high. The "safety first", insurance mentality, plus bureaucratic, "checks and balances" governments, have greatly reduced the possibilities of, and support for, socially positive excitement, so some people turn to other forms.