but, absent that, Durin's folk were generally good people (some of the other Dwarven houses less so). Above all the cherished their fathers and father figures, especially the kings.
Khazad-Dum was their truest homeland, but reclaiming that was beyond hope whilst The Bane of Durin held it against them. Vengeance (almost as improbable and impractical against a great dragon as against a great Maiar Demon, save for great luck and fortune) certainly drove Thorin. That is stated in the appendices. He wanted the gold, but I don't think that reclaiming his home was a small matter to him, even with the gold aside.
There was virtually no hope for gold in Moria, and a certainty of great loss of life, but the Dwarves went to war on all the orcs of The Misty mountains in grievance over the murder and maiming of Thror. And after Thrain still wanted to reclaim Moria. It was a non-starter. Dain had glimpsed The Balrog waiting for more of Durin's heirs just beyond the gate, and knew that entering was a fool's errand, but the desire remained, and that was not merely a desire for treasure.
You make a good point. I believe the movie is presenting Smaug as having seized Erebor for the treasure, the space itself being incidental. But to the Dwarves, Erebor is their homeland, and they want to recover that, with the treasure being secondary (except for the Arkenstone, which is of immense value to Thorin).
Tolkien's Dwarves were actually a good deal more venal than this, especially Thorin. Thorin is getting the Boromir treatment IMO (i.e., a noble, sympathetic character with a weakness).