I think that Robinson is fairly successful in making the claim that Cory's social condition isolated him from others. The social condition that Cory experiences is one in which wealth constructs a reality that objectifies him in the eyes of others. This is a state of being in which there can be no real understanding of him as a human. Rather, Cory is seen as an object of materialism, a glittering lure to others of what can be in their own lives. Robinson is fairly direct in developing this idea:
And he was rich - yes, richer than a king -
And admirably schooled in every grace:
In fine, we thought that he was everything
To make us wish that we were in his place.
Robinson is fairly successful in being able to develop Cory's characterization as one in which wealth has severed connection to others. The social configuration in which Cory lives is one in which others toil, using him as an example of what they wish to be without a full acknowledgement of his condition as a human being in his own right. To this end, Robinson suggests that social class and material reality shapes his being to the extent that it is this state that compels him to see suicide as the way out of it. His personality becomes impacted by wealth because it is this wealth that cuts him off from others, preventing any real social communication and interaction to take place. For Cory, his wealth could not silence the shrieking nothingness that strikes at his being. Additionally, I think that it is here where Robinson is his most successful in being able to argue how Cory's social class of wealth was one in which a profound influence on his personality becomes evident.