I agree with you about the condition of the parents before having children, but do you think this will prevent misery from the children's life? It might reduce it, but not eliminating it. Misery is a huge part of life, and "those who don't cry, don't see" as Victor Hugo said.

Parents may have children for many reasons, but for sure one of them is not the benefit of the child. Because what benefits are they for the child to exist in the first place rather than non existing? I can say most if not all the reasons of having a child is for the benefits of the parents themselves not the children. They make them feel happy, they give them social and financial support when they grow up while parents are old, ... etc.

The children when they grow up they will feel the same way, and the cycle continues. That's what I meant by humanity is stuck in a cycle of misery.