The deli owner and the bar-keep
Let's say I finally own that bar I've always dreamed of. One day I take a dollar out of my cash register and go over to the deli, where I buy a sandwhich. Later that evening, the deli owner shows up in my bar with the very same dollar, and uses it to buy a beer.
Back and forth the dollar goes, from one cash register to the other, buying sandwiches here and beers there. What's the end value of that dollar?
Well, sadly, when it comes time for me to buy a new keg, and for the deli owner to re-stock his fridge, that dollar is only worth 100 cents. The multiplier turns out to be 1. We didn't create wealth, we just consumed it.