Even Elon seems to have not done the proper analysis on the "overpopulation issue" judging by some public comments he's made to that effect.
You really need only spend 30-60 minutes reading up on the empirical evidence showing the population explosion has already happened and global population will level out at 10 to max 11 billion people. Poverty is disappearing very fast (thankfully) and with it the birth rates of poverty. Families in most countries in Africa, Asia and South America have already assumed the birth rates of "the developed world".
The reason we humans are such a problem for this planet is not the number of us, but our greed as short sightedness.