Here’s a thought:
You have a handful of elites and those who fancy themselves such (MSM/Hollywood/Libs) wanting a nice little planet to call their own...but all these nasty proles keep reproducing and making Utopia impossible. They hold the global reigns of power. So what to do?
Create a multi-pronged plan to instill fear on the population and turn it against itself. Spread chaos with claims of environmental apocalypse, destabilize world institutions and force the co-existance of people of disparate cultures/beliefs. Collapse an economy or two. Cut off cheap energy. Reduce quality of life and the hope for a better future. Desensitize the population to violence, killing and overall death.
Then when the people scream for an end to the madness, you push them over the edge into attacking each other, war, famine and disease kill off the majority of the world population, the elites shove the remnants of civilization onto some island/corner of the world to live as best they can or just enact a final solution ...
And they live happily ever after. The end. Now some people think that’s a deranged horror-fantasy. The same sort of people thought the same of Hitler, Stalin, Mao and Pol-Pot.
Anyone looking honestly at the progression of world events would be hard pressed to deny it as the ultimate outcome IMO.