Why are the Socs and the greasers separated by money?

Lack of money makes life harder for the Greasers in The Outsiders. Superficially, they don't wear flashy clothes, and they drive beaten-up cars. Psychologically, they're looked down upon by society. Unlike the Socs from the tony West Side, the Greasers are thought of as hoodlums. In fact, the Socs aren't even a gang; they're a social club.
While being poor and from the East Side separates the Greasers from the Socs, it also unites the Greasers. Unlike the status-conscious Socs, the Greasers are a family. They look out for each other and consider each other brothers. They don't flaunt their membership in a gang the way the Socs do. The Greasers want to get out of the gang and get out of the East Side—for good.