Very, very few people have extra money to invest when their child is a baby consistently until their child is old enough to attend college.
Many people who make 200k didn’t make 200k when their 18 year old was a baby.
This is going to be a major cliff of ability to pay as younger generations of parents become the parents who are paying for their now minor children to attend college. These are the parents who were laid off from corporate downsizing in 2008, 2020, and recently.
The ability of high income applicant families to pay is going to fall off a cliff in the next decade plus at the same time that the population of children in the US accelerates its decline.
It’s not the job of the federal government to tell colleges what to do to manage these social changes. Administrators need to take the initiative to educate themselves about the forces in the broader American economy and the impact that those forces have had on even high income families. If they continue doing as they are doing, that 50% that is full pay will be increasingly generational wealth, not self pay, and there is far less generational wealth in the US available for young people to go to college than there recently were and still are parents who were old enough to benefit from the economic opportunities present in recurrent recessions. That’s what you are describing.
Admissions is the least of college administrators’ problems.