Why does the great Gatsby end the way it does? Does this work out?

The novel ends the way it does because there really is no other way for it to end.  As a modern tale, The Great Gatsby is a reversal of the way stories were told in the 19th century.  In the typical "old fashioned" story, the good guy wins (and gets the girl) and the bad guy loses.  In modern storytelling, the bad guy wins (and gets the girl) and the good guy (in this case, Gatsby) loses. In fact, all of the characters in the novel who represent innocence, human potential, or are caught in the power struggles of others (Gatsby and the Wilsons, namely) are the ones who end up dead.  They are the dreamers. The vile characters (Tom and Daisy) get off scot free.  Nick is detached enough to recognize the tragic elements of Gatsby and the Wilsons and the shallowness and hollowness of people like the Bucannans.  This is why he spends the last page of the novel reflecting upon these events on the shore watching boats go by and pondering what the old Dutch sailors must have seen when the first beheld Manhattan and Long Island in the 1600's.  Fitzgerald suggests that in the modern world, the dreamers, who hold on to the ideals of America's romantic, agrarian past cannot survive.  Those who embrace the ideals of the modern world--industrialization and modernization--thrive.