Why Americans think that nobody likes them
well there are a few reasons imo.
1. America has appointed itself the worlds policeman and Americans think that many people in the world don't appreciate all of their hard work.
2. When you grow up in America you are taught that America is #1 and anyone that doesn't believe that must be against America.
3. The mentality is generally one side of the other. dem or repub, either you are with me or you are against me. The middle ground doesn't exist much in the general mentality of the public and therefore if someone is critical of America than it is assumed they are against it or doesn't like it.
4. Because it is true. Many people in the world are feeling that they are tired of America and its oppressive regime and the false confidence of its people. After the WW's people in much of the world loved America and what it stood for but the recent past has erased much of that feeling.
5. The government and media doesn't necessarily represent the people. People are people and most Americans are good people just as people are everywhere. Unfortunately, they tend to be manipulated by the media/govt/big business into supporting unnecessary wars which only benefit the rich class (govt contractors) and get left with the payment to bail out big business.
IMO people don't really hate Americans as much as they think they are generally less educated/cultured and not sufficiently aware of the rest of the world.