It's called hedonistic adaptation. Most people scale material consumption with income, and the new consumption level quickly feels normal. If this happens to you, then it's plausible that children will always look expensive, no matter your earned income.
The quality of life that modern, affluent people consider unacceptably low for a family would be considered decadent by most people who ever lived anywhere.
Sure, I'm saying maybe we should distribute public funds to reduce or minimize the affect of having children on your quality of life, if we agree that having children is a public good.
The same way that we give people tax breaks for making donations, because we think making donations is good, people having children are donating their time, physical health, money, and earning potential to the greater good of society, so maybe they should be compensated for it.
Regulating with positive feedback is usually unstable and rife with unintended consequences.
Can we start by striking down regulations that make having children more expensive? Zoning laws, environmental laws, development approval processes, and even building codes have significantly increase the cost of housing. Regulations made daycare prohibitively expensive, while also subsidizing that model over traditional childcare models. High costs are first order effects of these regulations, but there are plenty of second and third order cost increases as well.
The quality of life that modern, affluent people consider unacceptably low for a family would be considered decadent by most people who ever lived anywhere.