Pip and Magwitch are both outsiders. Magwitch is a career criminal, an outcast from decent, respectable society. For his part, Pip is never quite able to shake off his humble background as a "common laboring boy"—to use Estella's hurtful reproach—even as he cuts quite a dash as a man about town.
Guilt is a common theme throughout their respective lives. In providing a substantial sum of money to enable Pip to live the life of a gentleman, Magwitch is in some way atoning for his abandonment of Estella due to his pursuit of a life of crime. From an early age, Pip feels a nagging sense of guilt at having outlived his parents and five brothers. It is no wonder that he wants to be someone and be somewhere else. Yet even when he becomes a gentleman in London, guilt is never far away from Pip. He beats himself up over the snobbish way he treats Joe when Joe comes to visit.
Both men also come to realize that money is not everything and can never buy you happiness. Magwitch makes it big in Australia by becoming a successful, wealthy sheep-farmer. Despite this, he is still haunted by the demons of the past personified by the figure of the devious Compeyson. Pip initially enjoys his life as a moneyed young man of leisure in London but eventually understands how relatively unimportant it all is. What really matters in life is the love, companionship, and support that he can only truly receive from those who have always cared for him.