Anarchism is not just taking down the current system and saying "No system!" It is itself a system and an ideology around how people rule themselves. We don't seek to destroy, we seek to organize new systems and build that up. The point of the black bloc and other agitators is not to seriously overthrow the government, we know that isn't going to happen. Not any time soon. It's agitprop both to shake up the libs and make them realize that things are not ok, and also a call to like minded individuals that people are fighting back and organizing and to come join us. The actual revolution won't be kicked off by a bunch of angry youth. It will be kicked off with a sufficient amount of people have become class conscious enough that the people will rise up. Most likely that will occur after decades of organization, and more than likely after the collapse of our current society anyways. Which based on how capitalism is destroying itself and the working class, is definitely on it's way (not saying any time soon, just that it will happen, just like how feudalism destroyed itself).