One problem with killing 90+% of humanity, is that most every mechanism they might try would be pretty hard to keep from being turned on them, as, biologically at least, they are human too.

So, things that make you easily differentiated from them, for instance by living out in the woods off the grid, can make you easily targetable.  I posted a while back that the only real difference between 'them' and 'us' is that they're rich as Croesus, while we're not.  If they can devise a way to make the lack of money fatal, their problem is solved.

I saw past the optimal population level paradigm decades ago, and hopefully the things that convinced me will convince them as well.  It isn't the number of mouths to feed that causes ecological degradation.  

It's poor management.  

Thanks!