There is too much to address in a comment, but It is unfathomable that they would want to reduce the population to 500 million. Really that they would decrease the population at all, because current estimates believe it will plateau below 10 billion....that's even the UN's estimate. That is because developed nations have less children further along in their development. Now, if any body has the means to control the world in that way, it would be through monetary manipulation and suppression. Money is the key because it gives the people the illusion that they can control and have influence in their fate. Killing people would result in violent uprising, but money is subtle slavery.