Ideas do have some power, but these are ideas which are promulgated by tradition and propaganda. But even such ideas are no match for the private ideas of a dictator who has at his disposal a sword — money, weapons, police, and soldiers.
A current example of the impotence of ideas is the worldwide protests against the Iraq War on Feb 15, 2003. Here is an article about this:
Paul Blumenthal, “The Largest Protest Ever Was 15 Years Ago. The Iraq War Isn’t Over. What Happened? Can anti-war protesters claim any success?” Huffpost, March 17, 209
And here is a video about the Iraq war protests around the world, Feb 15, 2003: