Parents of children in poorer countries rely on them as domestic slaves. The more girls they have, the more boys they can support. But there is no reason to have children to help you the same way there is no reason to plant trees for CO2 capture - both will be destroyed before they become net positive.
You get it. God and other reasons are just excuses for their selfishness and greed. There is no love involved except narcissistic delusions. If one is very poor, then one should not have children.
Its such a modern failure that we accept so many people are not there who should be and populations and countries are shrinking in many parts of the world, this is a kind of self defeat others think it best somehow.
At this point a stable population would be much better than growing and of course than a shrinking one. Population does not need to indefinitely grow, and there is nothing wrong with short periods of shrinking either.
The powers that be may tell you otherwise, but they are lying.