I also want to point out that they don't pay taxes to their city, county, state, and country. There have been several studies by the CBO[0 - see the chart on page 31] that show that the lower 60% of households are not net tax payers at the federal level to such an extent that their entire non-federal tax payments offset by the transfers and benefits they receive from the federal government.
0 - https://www.cbo.gov/sites/default/files/114th-congress-2015-...
You're also forgetting that those workers exist. Beyond taxes the benefit of workers is also in the products and services they provide. When you're a retiree you still need someone to stock shelves in the supermarkets and sit in front of the cash register or someone to work on a farm and pick up the harvest.
When these discussions come up, I often think about this simple chart:
https://i.redd.it/pg5w8ws3b0o31.jpg
If the distribution of wealth, i.e. access to resources, were what 92% of Americans considered ideal, we'd need the minimal social programs you seem to want, and your low-wage worker in Renton would probably pay nothing to support a poor kid in Mississippi.
The current wealth scheme in the US is very much a consequence of US politics, i.e. taxation, wage laws, etc., it's not a natural state of being. (There is no natural state of being for a society.) What we have now is the result of choices made over a long time; getting different results, so you'd never be on the hook for someone in Mississippi, would take different choices from society, not just you declaring that we cannot afford and therefore should end social programs.
Changing post-tax income distribution is fairly straightforward (in theory), but it's less clear to me how to change wealth distribution.
Well, the direct answer is: these are all Americans, and all pay some kind of tax to their city, county, state, and ultimately the country, in theory so they can draw on the shared resources of the nation. That's how you justify supporting the kid in Mississippi and not the kid in Cambodia.
As for rationally holding the belief that people can have as many kids as they want, and those kids will be cared for, yes, you can hold those simultaneously. I don't want any kids in my country to go hungry; how many siblings they have or what choices their parents have made are irrelevant to those individual kids' needs being met. There's no conflict there.
We live, as they say, in a society.