Earlier quoted context omitted.
I suggest that the costs around children are a marketing scare tactic from people who want to create a fear of having children.
You said, verbatim: > There's no better investment. I then asked how is this an _investment_ for the parents. Can you explain that? I didn't ask about the off-tangent hypothesis, but the investment claim.
If your goal is to get into a debate on the financial returns to yourself based on children as some sort of investment vehicle then this won't go very far.
At a macro level, without children human civilization ceases to exist. That's the extreme case.
At a personal level, you have to look an intentional decision not to have children and compare it to the alternative. I am not including those who are unable to have children in this because I have known many couples through my life who weren't able and I fully realize what a difficult subject it is.
For those who chose not to have children, what is the ultimate financial or life goal? To have more disposable income to buy stuff, eat more fancy dinners? What's the point of investing or saving if you won't be able to pass it on?
Choosing not to have children is the result of years of pandering influence trying to convince people that they can't afford it, they aren't good enough, they'll be less happy, they'll have less avocado toast or a less important career. The goal of the marketing is two fold: either a) pander to a person's selfishness and convince them of all they will lose by having children or b) pander to a person's selflessness and convince them that the world is an overpopulated, terrible place that no compassionate person could possibly bring a child into. Both are coordinated messages designed to convince you not to have children.
Having children, on the other hand, ensures continuity of civilization. Ensures continuity of your family. Everything that you have learned that you feel value to pass on you get to teach to your children. You get to watch them grow up, teach them lessons from your own life, watch them become good citizens helping other people, falling in love, starting families of their own and contributing to society. You spend your life guiding them, helping them through difficulties.
All of the investments that you make financially can be passed on. You teach your children the financial lessons that you've learned and about the areas you wish you knew more about so that they may be able to be good stewards and improve on it from there. You teach them to be generous, to be charitable, to volunteer. You get to watch your children, grandchildren and sometimes even great grandchildren grow. And when you get old, that same family is there to care for you in your time of need.
Everything about your children is a multiplier of your family's values; your values.
Some of the people I mentioned who couldn't have children of their own chose to adopt. Some of them poured their time and energy into the service and education of youth. It's working towards the same goal.
Having children is one of life's greatest gifts. The institutions going out of their way to try to convince people not to have children are some of the most malicious that the world has ever known. If we were to ever quantify the number of lives that simply don't exist today as a result of those messages, the toll would be extreme. For people who have fallen victim to those messages, I hope there's still time to realize the truth.