There are many reasons to have children. These are mine.
I have purposefully avoided subjective ideas and stuck to something I find will be more universal.

I learned from my two years’ experience that it would cost incredibly little trouble to obtain one’s necessary food, even in this latitude; that a man may use as simple a diet as the animals, and yet retain health and strength.

Walden by Thoreau

I have come to the same conclusion as Thoreau. It's easy to provide only for yourself.

Using the surplus of my production ⁶⁾ to raise children is the best use I was able to find. Giving it to them and seeing them grow is the most worthwhile consumption I have found.

What will you do with your surplus?