Why does media control the world?

I have always noticed how media affects everyones life. The news for example. If they said that eating chocolate everyday will kill you, and then a week later, they say scientists have discovered a peice of dark chocolate everyday is good for your heart. People respond to everything on the media. Or MTV, teens watch that show, and look at how girls dress. All im saying is people are puppets, and the media is the puppeteer. If people know the media is just bull, then why do they rely on it so much? please put your opinions, theorys are all welcome