Many of [J. R. R.] Tolkien's contemporaries, writers such as Sartre and Beckett, depicted a universe that seemed purposeless, one populated by people whose lives had no real meaning. By contrast, in The Hobbit we find a world charged with a special kind of purpose—one which is beneficial in a particular way for both the individual and the world he is a part of. This purpose is similar to the one which is a part of the foundations of the Christian faith.
In chapter one when Gandalf tells Thorin and the dwarves that Bilbo is the "chosen and selected" burglar, it is hard not to share the dwarves' doubts and disbelief. As someone accurately described by Gloin as looking "more like a grocer than a burglar," Bilbo displays little in the beginning that suggests he will be an asset on the quest. His most defining characteristic at this point seems to be his excessive need for the comforts and safety found in his snug hobbit-hole—his warm fireplace and kettle, his cakes and fine waistcoats, and his pocket handkerchiefs. Even five chapters later when the dwarves discover that Bilbo did not escape from the goblins with them, the consensus is still that he has been more trouble to them than use.
So why was Bilbo chosen? The answer, we discover, is two-fold. Bilbo has a greater potential that only Gandalf—and whoever has sent Gandalf—can see. This forms the basis for the entire story. The adventure is going to allow a part of Bilbo to emerge which needs to emerge. Through it he will become the hobbit he was intended to be. We could say that the adventure will be the making of him. And at the same time, Bilbo has been chosen, not just because the adventure will do him good, but because he has something good to do for Middle-earth. The two purposes go hand in hand. Through the action of helping to save those around him, Bilbo will himself be saved, saved from a life bounded and surrounded by—as readers are shown—an inordinate need for predictability, safety, and comfort.
In chapter one when Gandalf first announced that he is looking for someone to share in an adventure he is planning, the hobbit replies that hobbits are plain quiet folk and have no use for adventures and that he cannot think what anybody sees in them. Although Bilbo and the quite residents of Hobbiton have no use for adventures and see nothing in them, Gandalf does. So does whoever Gandalf is acting as emissary for. While the stated purpose of the adventure is to get the treasure from Smaug, it soon becomes clear that the adventure has a purpose that goes far beyond merely getting the dwarves' treasure back.
When Gandalf tells the disbelieving hobbit that he is going to send him on an adventure, the wizard promises, "Very good for you—and profitable too." Exactly how will it be good for Bilbo and in what way will it be profitable?
As it turns out, the adventure is actually not that profitable to Bilbo, not in the sense that he returns home with the rightful share of the treasure he was promised at the start. Instead of a one-fourteenth portion of the enormous wealth of Smaug's hoard, in the end Bilbo brings home only two small chests, one with silver and one with gold, no more than can be carried by one strong pony. Although Bilbo and Gandalf also retrieve the trolls' plunder they had buried near the start of the journey, this too is not a large sum. The relatively modest amount Bilbo has left over after buying back his own possessions is largely spent in presents. In The Fellowship of the Ring when Strider and the hobbits come upon the stone marking where the treasure acquired by the trolls was hidden, Merry will wonder how much of Bilbo's share remains. Frodo will reply that Bilbo gave it all away as he felt it was not really his since it came from robbers.