The needs of the few out weight the needs of the many but this can be problematic because the "many" don't have necessary intelligence over diplomatic strategies, economics, politics, military etc and the majority can cause problems to a society in case they become "greedy" or dependent on the system. In fact, it is more likely that democracy is an idea in the sense that people think it's real when in reality there are a board of leaders in place making the decisions. It is also know that they aren't meant to last.
you should get both sides, that's what it means to be educated so why does your school ask you to get only one side...
it doesn't necessarily ensure the well-being in society, it isn't "all good" or even existent in most cases only believed to be in place.
even the school has an agenda, thank your teacher for not enlightening your class.