Excepting smart people like their kind, leftists view humans as a pox on the planet which ought to be reduced to the historical levels of about a half billion people which the planet supported prior to the invention of capitalism.
A few of the more the more enlightened leftists will tell you that thanks to improving technologies (which, of course, had nothing to do with the rise of capitalism) means the planet can now support two or perhaps even four times the historical level of half a billion.
I know this for a fact because when I was a young journalism major in college, I frequented coffee houses and other leftist hangouts and posed as one of them. They are quite honest in speaking openly about their intentions when they believe they are only speaking among their own kind.
Leftist just love their genocides but then they act like people are just bugs to be stamped on. Such snobs, you can see it especially when they are trying to cover it up by acting like they are the most compassionate people on earth. They do protest too much, must be hiding something.