Elon Mu$k is insistent that the population should keep growing, not stabilize or shrink. Many people had called for population control for environmental reasons. Mu$k wants growth for continued economic expan$ion.
If the population expands, there will be more children born who will have a lifetime of needs. Yes, they will also be con$umer$, but some will need significant social supports.
Also, if there are more consumers, there will be more environmental impacts.
If Mu$k wants this expansion, then he needs to be the billionaire leading the charge to raise marginal taxes* on the wealthy. These tax revenues will provide more services for those born with more needs and will pay for environmental clean-ups. Perhaps it could also provide more daycare and early childhood education free to more people (via vouchers, of course, so it wouldn't involve Mu$k indoctrination).
Instead, billionaire$ like him are fine with increa$ing the gap between rich and poor. But a larger population gives him more people from which to increa$e his own wealth. He and other billionaire$ need to pay higher marginal taxe$ on their upper earning$.*Marginal taxes: taxes charged only on income above a certain level or "margin." When people talk about charging higher taxes on the rich (this blog repeatedly calls for a 42% upper income marginal level), that percentage (i.e. 42%) is not taxed on the person's entire income, but only on amounts above a certain level, say, $500,000 or $1 million.