Memory and the past are everywhere in "Winter Dreams." Heck, the "Tone" of the story is wistful and nostalgic. On the one hand, Dexter wants to forget his humble origins. He wants to leave behind the memories of his immigrant mother and his grocer father, move to the East Coast, and make tons of money. Dexter's social success depends on his willingness to ignore his lower class background so that he can attach himself completely to the upper class. On the other hand, Dexter's eagerness to leave behind his social origins shows that he also has to sacrifice his own early memories. To make lots of money, he also has to turn his back on the romantic idealism of his younger days. Dexter appears perfectly fine with forgetting about his parents. (Nice, Dex.) But he weeps when he finally understands that he has also cast aside "the country of illusion, of youth, of the richness of life" (6.36) that used to inspire him so much. He has forgotten about the boy he used to be, which is the worst loss that Dexter can imagine.
"Winter Dreams" uses Dexter Green's sense of distance from his own past to show off the general flexibility of the American class system. (I.e. Dexter can go from humble immigrant parents to a future in which his children can afford "carelessness" [3.2] in just three generations.)
Dexter spends so much time in the past and the future that he forgets about the present moment. He would have had a more fulfilling life if he'd remembered to live in the moment.