The american dream is the belief that through hard work and perseverance we can all achieve greatness and be successful. This is possible because success is all dependent upon one's mindset. What one considers success may differ from what another views it to be. so we can all reach our own american dream based on our individual goals.
The ending did support the fakirs belief. At the end the White's most beloved thing (their son) was turned into a horrible monstrosity from the dead. This happened because the Whites wished for their son back from the dead. Upon this wish they tried to play God and messed with fate.
