Dickens portrays Pip as someone trapped by his own snobbery, someone obsessed with becoming a gentleman.
Eventually, Pip will break free from his snobbery and realize that he estranged Joe Gargery by his single-minded obsession with becoming a wealthy young gentleman about town. But while he's trapped in that obsession, he is imprisoned by social conventions that exert an unhealthy influence over him.
In showing us the damaging effects of this imprisonment, Dickens is engaged in a savage critique of contemporary society with all its snobbery and class consciousness. In such a society, one's social background is everything.
Even a man as rich as Abel Magwitch can't be accepted into decent society on account of his disreputable past as a convict. By the same token, Estella, for all her refinement, cannot take her place in society as a lady of quality once it becomes known that Abel Magwitch is her father.
They, like Pip, are imprisoned by the stultifying conventions of mid-nineteenth-century English society, where a premium is placed on social class rather than character.