Dill and Jem, on separate occasions, offer Scout ideas as to why Boo stays inside the Radley house. At the conclusion of Chapter 14, Scout asks Dill why Boo has never run away. Dill says, "Maybe he doesn't have anywhere to run off to . . . ."
Later, at the end of Chapter 23, Jem talks to Scout about Boo's behavior. This occurs after Jem has observed first hand the racial hatred in Maycomb and the injustice of Tom Robinson's trial and conviction. When Scout says she thinks that "there's just one kind of folks," Jem replies:
If there's just one kind of folks, why can't they get along with each other? If they're all alike, why do they go out of their way to despise each other? Scout, I think I'm beginning to understand something. I think I'm beginning to understand why Boo Radley's stayed shut up in the house all this time . . . it's because he wants to stay inside.
By the end of the novel, Scout has grown up enough to realize that both Dill and Jem were right.