Right, the thing is before you have children you can weigh the costs/rewards dispassionately, but after you have a child the calculus changes because now this person exists who is now the most important thing in the world to you. As soon as that person exists your life is no longer yours, it is in service of that child (assuming everything goes according to plan, of course it doesn't always work out that way), so of course rationalizing any cost at that point is just part of the deal.

I want my life to be my own, thus the costs are not worth it to me. If I had a kid tomorrow of course that equation would change and it would be in my best interest to rationalize all costs in service of the child, and surely I would and suddenly they would be "worth it." I do not view this as an argument in favor of having children, rather I view it as a a specific detail of the biological programming working its magic.

I'm not a never-kid person either. I am open to the idea that one day I may decide the costs are indeed worth it and seek to have children. I think that seems unlikely, but part of the freedom of designing my own life is having the space for my preferences to change, and I could envision a world in which I would be happy as a parent. It would not be in a nuclear family as is common in the west, but that is perhaps for another discussion.