It's self-perpetuating. People do mean things to other people because other people have done mean things to them or their group because of that group and the cycle continues. It doesn't help that people often fail to recognize the fundamental attribution error in play, either.
Many argue that an arbitrary division among the disenfranchised and poor is an effective barrier for them to rise up against the minority that hoard the resources for themselves. So one could argue that it does help someone.
One theory would be that humans have a biological sense of other. In-group, out-group, etc. People fight for the same resources, preferentially for their genetically similar groups.
If there are 10 people at a table about to starve to death, and only 5 of them are related, it helps their genetic lineage to prefer to feed relatives.
Racism, as an outgrowth of us-versus-them, most likely helped with keeping a lineage alive.
Does it help in anything?