Plato talked a lot about this. It's very easy for politicians to feed people things that they like but aren't good for them, and this is the normal course of affairs in history. It doesn't really mean anything bad about the USA in the great picture, because we're no different than the rest of the world. That being said, good things happen when "divine providence" (or whatever) produces leaders who feed the people things that improve their health. History in this way is sort of chaotic and kind of a waiting game. The best way to minimize the time in between downward spirals is by strengthening the fabric of society when you have the opportunity, by teaching them - for lack of a better word - how to recognize knowledge.