well, the "elite" have been whispering wistfully about eliminating the majority of the population for decades.
rather memorable was when some prince wanted to come back as some virus to "solve the population problem"
see thats the thing, you Cant control that many people. scares the shit out of them.
and its true, they dont really need that many slaves anymore, thanks to modern advancements in technology.
and it would be easy to convince a few slaves to be allowed to be kept alive.
but how would you do it? virus? viruses mutate, unpredictable things.
soldiers rebel and if you´d get enough of them, some would reject the notion of killing their own grandmothers.(plus soldiers would be unneeded in the new world or at least not that many, some would wise up to that))
outright global war? too much risk of destroying the planet (at least for generations)
robots? too many people.
possibly if there were nanobots that would just disassemble all humans into manure and the odd furniture.
but doubtful, that would be a rather massive project, undoubtedly someone would talk.
anyways, if the people dont wise up, nature itself will take care of the problem.
the planet could support us
given that the planet would unite (so the planet could be used reasonably)
and people would stop breeding like crazy (which they do with education)
without the threat of war, there would be more than enough resources to support us even if we didnt stop breeding (check out how much it costs to school and water the world and then check just the us army budget)
without all this waste (making crap in the hope of people buying it(making things crappier so they will fail sooner so people need to buy again is another waste(and so on and so on)))
and stupidity (war, (cockfights(im the better dick!))), this would be heaven.
absolute paradise.