"Just as you want people to treat you, treat them in the same way" - Jesus (Luke6.31)
I had always thought of this as a verse about ethics - you ought to live this way because it is the right thing to do. But a few weeks ago I was going through the story of Jacob with the kids for homeschool. We talked about how Jacob schemed and lied to get his birthright and blessing, and how later on Laban tricked him with his wives. There is an implicit argument here that you WILL be treated as you have treated others. Of course the argument is not explicit, and perhaps not everything we do in this life will have direct repercussions in this life - but often they will. So I think Jesus' statement is not so much about ethics as about wisdom, learning how to live your life in accordance with God's spiritual laws of the universe.
The golden commandment, then, is quite similar to Paul's assertion in Galatians 6.7: "Do not be deceived, God is not mocked; for whatever a man sows, this he will also reap." I wonder how many times the things that happen to people are the spiritual result of things they have done earlier in life. And the people who cry most loudly, "Unfair, unfair!" are actually reaping what they sowed.
Of course, the book of Job reminds us that not everything that happens to us is the result of our actions. But let us not conclude from it that nothing is.