When all the customers die off, the market will regulate itself.
The further the negative affected is "away" from the one who gives direct marked feedback the less does marked self regulation work.
Similar the more the negative effect is subtle affecting people often in a non-obvious roundabout (but potentially still massive) way, the less does free marked self regulation work.
Which on our modern Globalized, hyper Complex, high tech World means:
It can't work well, potentially not at all in some areas.
Some of the statistically overpopulated countries work okay with it (e.g. Singapore, Japan).
Most of the "problem causing" over population is in Asia and parts of the middle east. (Which doesn't mean they cause problems for others, but there are overpopulated countries which have "some" problems cooping with it.)
So why should any regulation affecting mostly Western states at all matter wrt. over population?