This isn't quite true. While it is the case that the elites are happy to see zero or negative population growth in America and Europe, they also want a huge pool of cheap and pliant labor, i.e. coolie IT employees from India and China, farm and unskilled manual laborers from Latin America. So they're all for a world overrun by billions, as long as those billions are Third World people who obediently work a plantation for peanuts.
Yes, it is true. They do not need billions of low IQ wage slaves as you claim. They have stated the 500 million number many times.