Let’s run some numbers.
Suppose a husband and wife in California both work, and they both make median income, which we will round to $35K per year. They have two children, and the oldest is now ready for college. She is very bright, near the top of her class, and gets admitted to UC-Berkeley.
Running the Net Price Calculator for UC-Berkeley, the in-state list price is about $39.2K. But with their $70K income and $100K in assets, they get a $24.3K grant, reducing their total contribution to $14.8K per year, or roughly $60K for 4 years in constant dollars. Of that $60K, they expect the student to cover about $36K through work study and loans. A student can earn about $5K during the summer at the California minimum wage, plus some more during school-year work study, so the loan component should end up being small.
The other $24K is from parental contributions which hopefully the parents were able to save up. If not, they can take that out as a parental loan.
And let’s not forget that there are cheaper options as well. UC-Berkeley’s transfer program gives first priority to students from California community colleges. California’s community colleges charge $46 per credit hour. The student can stay at home, earn 60 credit hours over two years at a total cost of $2760, and then transfer to Berkeley, and graduate two years later. Same quality degree, but about half the cost.
All possible on middle-class incomes, which as I said, are considerably higher in the USA. No plutocrat wealth required.