Why do we fight?

Surely, some will answer that we fight for peace, but that's an impossibility.  To fight for peace is to destory a house to add a room.

Others argue that we fight for justice, but that, too, is absurd.  We have no common definition for justice, only personal meanings that vary wildly.  Communists believe true equality is just, whereas a Representative government advertises majority's rule.

Perhaps we fight for revenge.  But that leads to a question; who made the first offense?  Why?  For money?  Power?  Land?  No, in a peaceful society there would be no need to fight for these.

That leaves only the single, horrible possibility.  They fought for fun.  Violence started as entertainment and continued for revenge.  People didn't realize how precious life is and spent it needlessly.

But does anyone realize this even now?  We still wage wars for nothing, have fights for fun under the guise of sports.  The Olympics are meant to be a mission of peace, but they're a competition that easily turns violent.  And even if these wars were absent, we fill our lives with boredom and do things to kill time.  Who really values life?