One of the most important themes in the book is that it is better to be good than rich. I think a good example of this is Joe.
Joe is a good person. He never wants more than he has. He takes care of Pip, even though his wife is abusive. He genuinely wants what is best for him.
Joe does not even want to take money from Pip, even though he could position himself to benefit from Pip’s fortune. Almost everyone else in the book tries to take advantage of him, but Joe never does. He only feels grateful that Pip is taken care of and misses his company.
“Lord forbid that I should want anything for not standing in Pip's way,” said Joe, staring.
“Lord forbidding is pious, but not to the purpose,” returned Mr. Jaggers. “The question is, Would you want anything? Do you want anything?” (Chapter XVIII, p. 97)
Even after Pip forsakes Joe, and is clearly ashamed of him, Joe never stops caring about Pip. He is a perfect example of the honest, humble man who is a gentleman in character and not wealth.