The Question and Answer section for Catching Fire is a great resource to ask questions, find answers, and discuss the novel.
The media controls the Capitol and is just a tool of President Snow to spread propaganda and lies. This is how he controls the people.
I suppose when people are suffering themselves they try to look after themselves before helping others.
The Capitol isolates and starves other districts. They keep other districts ignorant and competing against each other for survival to actually challenge the Capitol.