Smaug is a dangerous dragon
He stole the Dwarves treasure and destroyed the Town of Dale. He loves treasure and is truly fearsome. How are the dwarves and Bilbo going to rescue their treasure now? He is inside the Lonely Mountain lying on top of the pile of stolen treasure. He is powerful and huge and can live for centuries. He breathes fire!
(this image is from the 1977 film version of the story)
(this image is from the 1977 film version of the story)