Why is a dictatorship not the best government?

Because you're putting an awful lot of power into the hands of one person, and people tend to get crazy and act evil when they have unlimited power. Look at countries like Libya and Cuba. They had dictatorship governments and because of that the people suffered immensely 

Dictatorship are bad because it does not allow for the evolution of man. Man can't be what he want's to be under a dictatorship. Also the problem with a dictatorship is most of the capital created by the country goes to the dictator themselves. A third problem with dictatorship is they make all the decisions for that country such as when to go to war, where money goes into the economy and etc.