it's definitely 500 million.

they want to live with a certain protocol and have calculated how many people can be sustained for thousands of years.

the amount of oil, gas, water, these aren't really the only limited considerations, it's all the stuff like gold, copper, lithium, rhodium, platinum, all these rare earth elements that are now used in mass production just aren't plentiful enough.

a billion killed would grow back in 10 years, that would be utterly pointless but most people wouldn't think that far into it. most people are FOR depopulation as long as they think it's not them.