The American Dream is a journey with no destination
Dressler's pursuit of market success likely comes to the reader as a morally great thing. For the son of a humble immigrant to understand that America is the land of true opportunity comes alongside the dominant narrative that exists in America for a business-centric, successful life.
The theme arises in the lack of resolve. According to the American ideal, the audience expects to see Dressler sitting back to enjoy his accomplishment, to enjoy the meaning that success should have brought him. But actually, the character remains stuck in his all-consuming belief that a bigger, better success is around the corner.
Meaning doesn't necessarily come from the fulfillment of desire
In Dressler's relationship to Caroline, the audience sees what could have been a wonderful opportunity for meaning through relationship, romance and family. But Martin's one-track mind, although it leads him to success, also leads to a long road of missed opportunities, because the meaning available to him didn't lie on the other side of his desires.
To see this theme more directly, Martin's obsessive desire for success never actually pays off. It's an insatiable hunger without the ability to lead to fullness.
America is actually a land of opportunity
One would assume that a novel about the emptiness of the American Dream would show how impossible the Dream is to accomplish. But Millhauser wisely allows his main character to climb through the corporate ladder and to attain a great deal of success along his journey.
Therefore, the novel does not argue against the validity of the American Dream; it only argues that it cannot be where one draws their meaning, because it's an engine, not a destination.
The thematic question of money
Perhaps one of the central ironies of the book involves Dressler's relationship to his wife's sister, Emmeline. The nature of their relationship seems to stem from Emmeline's willingness to invest in his projects. The thematic question of whether it was wise for Dressler to orchestrate his social life based on money alone is asked, but not answered, although the answer is implied in the question. If the American Dream is meaningless, so also is money.
The disappointment of power
Part of what the American Dream means to Dressler is a validation of his internal thirst for power. He could have had a brilliant career opportunity at the hotel where he was offered the Assistant Manager position, but he refuses that position. That opportunity is fully part of the American Dream, but for Dressler, a deeper desire becomes clear: He wants to be the god of his own organization, without being beholden to upper management. This desire for power may be at the root of his quiet, under-spoken dissatisfaction with life itself.
