Or if you're very poor, then the more kids you have, the more you receive in benefits. Many poor people manage to have more kids than middle class people.
The middle class parent thinks "if I have another kid how will I pay for their college?" The poor parent just sends their kids to community college or if they're amazingly brilliant and get into Harvard, then they'll get a free full ride because they're poor.
But, the result of all this psychology and zero-sum competition (as housing/schools are) is that kids tend to eat all available income up to a point—and, indeed, if you cross a certain income threshold and can afford top-tier private school, there's another entire tier of potential and hard-to-convince-yourself-not-to-do spending above that.
Our three kids are gonna cost us at least half a million dollars by the time they're all 18, between lost income, daycare costs, higher housing costs (not just a bigger house to maintain a similar comfort level, but also one in a much more expensive area than we might otherwise live in, since we have to care about school quality—an uncomfortably small house in a good school district still costs more than a huge house in a merely so-so district, let alone an actually-bad district, in our city), healthcare costs, transportation costs, plus all the smaller stuff like clothes, food, et c. And e.v.e.r.y.t.h.i.n.g optional is also far more expensive, like vacations.
And that's if we don't chip in for their post-secondary education or, like, give them a few grand to get their feet under them when they leave. Or buy them cars or any of that (we're not there yet, thank god). It could easily end up being closer to a million than a half-million, without even going nuts.
The tax credits don't even come close to covering it. Worse, because many of those expenses are front-loaded and so hit in our relatively-young years, the opportunity cost of that money ends up being enormous. The shadow cast on our future savings is way bigger than what we spend on them directly. We'd be retiring by 50, 55 at the latest if not for having kids, and also be able to spend more freely. As it is IDK if we're gonna be able to retire until we just can't work anymore.
Kids are basically financial suicide unless you're crazy-rich. Like they're great and all but god damn do I understand why people choose not to have them, even if they like the idea of having kids.