Magwitch's wealth, which had been supporting Pip—Magwitch worked hard and lived a rough life so that Pip could be a gentleman—goes to the government (the crown) because Magwitch dies as a convicted criminal. As Pip says:

I foresaw that, being convicted, his possessions would be forfeited to the Crown.

Pip shows his transformation and change of heart as his benefactor lays dying. After he first discovers the identity of his benefactor, Pip is revulsed to learn that his status as a gentleman is supported by a convict and rejects Magwitch's money. This reflects his snobbery and ego. He is offended to be getting his money from such a lower-class person as Magwitch. He is bruised too that Miss Havisham, who he always assumed was his benefactor, had no interest in helping him become a gentleman.

By the time Magwitch dies, however, all of this has reversed. Pip has come to see the worth of his benefactor and to look beyond outward signs of status to the heart inside a person. He comes to love Magwitch, and by the time of his death he doesn't care much about his money, because that no longer matters as much to him. Pip learns to value people, not their social status. As he writes:

For now, my repugnance to him had all melted away; and in the hunted, wounded, shackled creature who held my hand in his, I only saw a man who had meant to be my benefactor, and who had felt affectionately, gratefully, and generously, towards me with great constancy through a series of years. I only saw in him a much better man than I had been to Joe.