I'm sure you could imagine, if not understand, some reasons.
In countries without social insurance people have children so the child will take care of them in their old age.
can you understand why people consciously decide not to have them?
Yes that part is very easy. I can’t understand why someone would choose to give up their prime years for a child. The entire idea of retirement is a direct consequence of this. You don’t need to retire if you can you know, just continuously enjoy your life the entire time.
I think there's a direct comparison to be made with the choice to devote one's "prime years" to building a startup. It's a meaningful project that materially impacts the world in a way that one has a decent degree of control over. And it can be fun, even in the same moments it is deeply difficult!
Not really because you can just walk away from a failing startup. A startup can also profit, or you can hire people to take responsibility away from you, or even sell the startup. A child to me is more akin to a jail sentence in that you can’t escape without getting in even more trouble.
OP points his finger at the protonatalist conspiracy.