[BradyLS]

When we’re down to a billion people…

…there will still be a top tier and a bottom tier that will hate each other’s guts.

However enlightened, affluent, and “equal” that one billion is, there will still be a swath of malcontents who will agitate over any perceived disenfranchisement and make life miserable for those around them.

[ealgeone]

And there will always be another "professor" coming along saying we need to reduce the population further.

Or redistribute wealth; just not theirs.

[BradyLS]

…And there will be swath of insufferable people who lord it over the others and dream the happy day when humanity had been humanely reduced to just the cream of crop: 100 million souls. Just the right amount of people the world can support.