Because they never had a truly professional, disciplined army, they never expected such a huge resistance. They took thousands of casualties. If the U.S. had not intervened massively the Indonesian army probably would have been defeated militarily by the Timorese resistance force. So the Carter policy made a difference with a massive injection of weapons to Indonesia that changed the balance of power and prolonged the war for twenty years. I'm not sure of what kept me going in those dark decades.
Some people fight because they believe in world revolution.
But I am not an ideological person and I don't believe in world Marxism. Nor am I a fundamentalist Catholic who believes in the dominance of the faith. Instead I thought of the spirits of those in East Timor, telling me to fight on. I was totally isolated in the U.S. and could have gone and taken a job, like so many exiles do, defected and gotten on with my life. I went and spoke there.