In George Stevens' sprawling epic Giant (1956), the characters move through life on a Texas ranch, on which oil is discovered by James Dean's brooding ranch hand character. The film goes through his obsession with oil and it basically shows how his greed brought him down, despite his good intentions. Also, one of the more interesting things about this film is the subplot which involves one of Rock Hudson and Elizabeth Taylor's characters' children and his spouse, a Mexican-American. It is punctuted by the type of closed doors to minorities that were so prevalent before the Civil Rights era, but ends with Hudson's character getting into a fistfight in a diner in defense of his daughter-in-law.
There is also the brilliant film starring Daniel Day-Lewis, There Will Be Blood (2007). Directed by Paul Thomas Anderson, what is so funny about having this film on the same day as the previously mentioned film is the majority of both films were shot in the same small West Texas town, Marfa. This story centers more on Daniel Day-Lewis' character's greed and his emergence as the dominant oil man, through whatever means necessary. It also depicts a broad range of time difference and still retains it's focus as a film which is about Day-Lewis' character, not so much everything that is happening around him.
Dean and Day-Lewis' character's don't differ much in that both are greedy and seem to only need their money. Day-Lewis' character end up alone due to his inability to accept that other can have a stake in the way things occur or what happens around them. Dean's character ends up lonely and alone due to the fact that he thought money could buy him love and affection, when in reality it only bought him less of that very thing.