What does it say about the American Dream that Gatsby spends 5 years dreaming of Daisy?

The fact that Gatsby has spent five years dreaming about being reunited with Daisy shows us a couple of important points about the American Dream.
Firstly, it shows us something positive about the American Dream—that it can be achieved. Although Gatsby has waited for five years to see her again, five years is a relatively short time in a person's life. This suggests that, although the American Dream cannot be achieved overnight, it can be achieved in a realistic amount of time.
On the flipside, let's consider what has happened in the time that Gatsby spent dreaming about Daisy. Daisy, for example, has married Tom and had a child. She has made friends, such as Jordan, and experienced life. In contrast, Gatsby has done nothing but create wealth, in order to be with Daisy. Every other aspect of his life has, in effect, has stagnated. He has no real friends, for example, nor has he had any meaningful experiences.
What this shows us is that, although the American Dream is achievable, it often comes at a hefty price. For Gatsby, this price was the unconditional surrender of his life. Every ounce of energy had to be directed towards achieving his dream. Otherwise, he would have failed.
The American Dream, therefore, can be achieved by those who chase it. However, it demands total commitment and dedication, leaving neither time nor energy for any other pursuits.