Quote 1
"But [Dain and his dwarves] cannot reach the Mountain unmarked," said Roäc, "and I fear lest there be battle in the valley. I do not call this counsel good. Though they are a grim folk, they are not likely to overcome the host that besets you; and even if they did so, what will you gain? Winter and snow is hastening behind them. How shall you be fed without the friendship and goodwill of the lands about you? The treasure is likely to be your death, though the dragon is no more!" (16.5)
Roäc the raven isn't just a messenger. He also tells Thorin when he's being an idiot. For example, Thorin is counting on Dain and his reinforcements to hold the Lonely Mountain against Bard and the Elvenking. But Dain can't get into the Lonely Mountain without fighting his way through the valley where the elves and men are camped. And then what? Does Thorin just want to stay at war with everyone around him, just for treasure? Tolkien represents treasure as an actual sickness that can overcome your reason just like any other mental illness. This isn't his idea alone; according to Anderson's Annotated Hobbit, Tolkien gets his ideas about the maddening effects of treasure from the Old English epic Beowulf.