Money is a very powerful tool that can be used to answered all things on earth. Without money there are a lot of good things in life you can't have access to, and without money the world doesn't recognize your person that's why every individual person on earth strives so hard to have it. Without money you can not have good health care, good housing condition, better education, almost every good things of life is connected to money that without you can't have it or be it and that's why it looks like money now rules the world.
I personally prefer to call Money does not rule the world. but I prefer to call money as something that is considered the most important and most wanted and needed in the world today. Everyone needs money to buy the things they need. and all work hard to earn money to use as a means by which to buy the things one wants. But yeah, you are free to think of money as anything.
Well I like to think money is actually every thing since they have simply implemented that thought in the system of world today, as every one clearly knows without money its basically hard to live your life as money is the core source for us to feed, to house our self and to attain all the basic necessity of life.