Classical Athens offers a fascinating example. It was a radical democracy of citizens who certainly understood what they were doing, and it became the most imperially ambitious, expansive, destructive, and exploitative polis of the classical period. They put an entire city to death for refusing to join the 'defensive' alliance that they led and massively enriched themselves at the expense of member states.
Sure, but their society prospered and the actions of the state reflected the will of the people. That's a big caveat with democracy, it can only be as good as the majority of people.
