Actually the trigger for 1989 was Tiananmen Square, it provided inspiration to the people in the Captive Nations to rise up.
I am from one of these captive nations and disagree. The fact that I won’t go to jail or have my life ruined for “wrongthink” influenced me and others. We didn’t know about China.
Gorbachev thought that communism is good, but he needs to get rid of bad communists in high places. He reduced repression and censorship hoping that people will use their new freedom to help him to remove these incompetent commie f*cks.
To his great surprise people used this freedom to denounce ALL communism.