Actually, I think the desire for independence is an economic concern, broadly speaking. Apropos is a recent Zoom session on the cost of children that Aaron Renn held with subscribers (I watched the recording). Aaron pointed out that the monetary opportunity cost of raising children could be more than a hundred thousand dollars a year for middle class Americans. He furthermore pointed out that our society offers many more opportunities for leisure – travel, eating out, various entertainments, etc. – than ever before. These would need to be largely foregone to take up the responsibility of parenthood. I am thinking that the opportunity cost of raising children in terms of money and leisure may be higher now than it ever has been in history.
When it comes to money, children are a truly terrible investment. Raising a child requires a parent to either stay home and forego earned income or work and pay high costs for childcare. Unlike in past times when even young children could be economically productive on the family farm or shop, children today are a only a cost. Not only that, many years of schooling and often costly post-secondary education or training are needed to enable a child to become economically productive. So much upfront cost and delay before obtaining any return! And a substantial portion of the economic return gained by the child that could be used to support parents in their old age is instead taken by the government and given to strangers whether or not they have children contributing to the system.
In the post-industrial economy, the cost of having children is mostly internalized to parents and the benefit of having children is mostly externalized to society (e.g., workers for the market economy and taxpayers for the welfare state). So with the decline of religion, I think it is no surprise that fertility is declining as well.