Why the richest countries get the most medals such as China, Japan,U.S. Australia, Germany, Russia etc?

They way I understood it is... the Olympics aren't to see who can get the most "metals" but to unite the world under a friends sports competition... for fun, but yeah I guess the metals are cool too.Oh, and the "richest countries" you named aren't really the richest countries. If you're China and have 1/5 of the worlds population and you're a communist country... you're bound to have a few gold medalists.