1.) thin air
2.) the government (??? No.)
3.) higher tuition -> hint: pick this option!
The better question is why Harvard and Princeton charge tuition at all! (The answer to that question is not that hard either.)
Princeton has quite large aid packages outlined here: https://admission.princeton.edu/cost-aid
Harvard has different but also quite amazingly large aid packages for lower and middle-income students: https://college.harvard.edu/admissions/why-harvard/affordabi...
Wealth redistribution / market segmentation.
1.) thin air
2.) the government (??? No.)
3.) higher tuition -> hint: pick this option!
The better question is why Harvard and Princeton charge tuition at all! (The answer to that question is not that hard either.)