Earlier quoted context omitted.
I disagree that there are too many people. Have you read much about the Malthus/George debates? Malthus has now been wrong for 200 years (and counting).
There are whales full of plastic and the rain isn't safe to drink. How can adding more humans help??
On top of that, a declining human population results is an increasing young:old ratio. Fewer younger working age people supporting an increasingly older population. Socially and economically that will be a disaster, which will make solving ecological issues significantly harder.