Samsung is moving into the mobile network infrastructure market and hence is planing to become a competitor. This is probably the key for the dispute, Samsung will most likely use the IPR in other product segments than mobile phones only.
Ericsson has as well a 50% stake in ST-Ericsson, selling mobile platforms for manufacturers like Samsung. note, the S3 mini is based on an ST-Ericsson platform. Samsung has an own LTE platform as well. So Samsung is both a customer as a competitor to Ericsson in this area.
Yes, they do not compete on the mobile phones themselves but they do compete in all other areas. Stating this is only about the money or not is pure speculation. This is a rather complex situation.