They most likely believe that all greasers are poor and are not rich like they are. They also know that they are easy to be targetted by the greasers. Socs also believe that the greasers are easy targets to hate since they are like them.
Throughout the book we see that there is visible hate between the two groups, the socs hate on the greasers because they're poor, and the greasers hate on the socs because they don't have as much as them, and are always made fun of by them.
