There are three parts where population size directly relates to Government spending. Welfare, Healthcare and Education. In the UK you can add Housing Benefits and in the UK the Government subsidises business by giving the low paid welfare.
If the US had to stop all borrowing and run a balanced budget but kept the debt as high as it is now. You would all have to pay an extra $2,000 per person. In the UK the figure would be £1,000. That keeps it at the terrible situation it is now with no improvements.
That's the bill for buying cheap goods from overseas, automated factories, migration and not managing the population to the needs of the country. And it will only get worse.
Anyone over 60 can clearly remember better times. Those of you under 40 will see it slowly get worse, so remember I was right about your future. Unless you're one of the few who can keep pace with the rise in costs and can ignore those who can't.