In F. Scott Fitzgerald's The Great Gatsby, how have Jay Gatsby and George Wilson been affected by other characters' selfishness and greed?

Both Jay Gatsby and George Wilson were chasing the American Dream, and both were somewhat out of touch with reality in their inability to realize that the American Dream is really a fiction.  Gatsby felt certain that he could repeat the past, if only he could acquire the money to keep Daisy in the life to which she's accustomed.  He doesn't realize that being a bootlegger will tarnish both him and his fortune in her eyes, and that a criminal could never please her or achieve the American Dream.  Wilson, likewise, thinks that if he can just get a hold of Tom Buchanan's car, he can turn it for profit, enough to improve his situation and, eventually, to pave the way for him and his wife, Myrtle, to leave the valley of ashes.  Hard and honest work does not help him to achieve the American Dream, either.  The only way to get rich, then, is to engage in illegal activity (which shuts one out from the dream), and if one engages in actual, legitimate hard work, one can never earn enough to achieve the dream.  There is, simply, no path to it.  Gatsby doesn't understand that he can't reach the dream, and neither does Wilson, but they both continue to believe they can for the majority of the novel.  It is not until they are affected in a significant way by others' selfishness that they become disillusioned, and even Gatsby never really does.  After Daisy kills Myrtle and allows Gatsby to take the blame for it, when Wilson realizes that his wife's been cheating on him with Tom, Wilson finally realizes the hopelessness of his endeavors and takes his own life.  If Gatsby realizes anything, it's that Daisy is not going to call, that she has slipped from his fingers again.