How does Gatsby's life verify the theme "blind pursuit of an ideal is destructive"?

How is Gatsby's life like a Horatio Alger story?

This theme relates to Gatsby creating himself in the pursuit of Daisy. His whole existence is to win Daisy; a symbol of this is his looking longingly at the green light across the water. The water itself is a symbol of the distance between Gatsby and Daisy that can never be overcome. When Daisy rejects Gatsby at the end he remains true to his dream, waiting outside until she goes to bed after killing Myrtle, and then the fact that he dies because he has taken the blame for the accident that Daisy caused. It is also interesting that during the novel, when Gatsby and Daisy get together Gatsby is overcome by darkness, the lights at his mansion go out and he stops having parties. The destructive nature stuff relates to the fact that Gatsby's whole life ends up being so senseless, he created himself and his wealth for Daisy and then is completely rejected and destroyed because of it. You could also talk about the fact that no one seemed to care enough when he died to come to his funeral. Hope this helps (it may be a little incoherent!)