Students walk on the Stanford University campus Thursday. (Ben Margot/AP)

IT IS appalling that wealthy parents willing to pay bribes allegedly used what the architect of a recently revealed scam called “a side door” to get their children admission into schools such as Yale, Georgetown and Stanford universities. That a legal back door exists for families who have connections or make big donations to private institutions should also be of concern. But the biggest problem in U.S. higher education are the closed doors that still prevent far too many young Americans from getting a college degree.

Considerable progress has been made in increasing the share of students who graduate from high school and immediately enroll in college. A report by the College Board in 2016 found an increase from 51 percent in 1975 to 69 percent in 2015. But that same report also noted a persistent gap in enrollment across income and demographic groups. In 2015, 82 percent of high school graduates from the highest income quintile (above $100,010) enrolled in college, compared with 62 percent of those from the middle income ($37,000 to $60,300) and 58 percent of those from the lowest income (below $20,582). Black and Hispanic students lag behind their white peers. Moreover, those who begin college do not always earn a degree; about 1 in 5 full-time freshmen nationwide don’t return for a second year. Data from the National Student Clearinghouse Research Center shows that more than a third of students who start college haven’t earned degrees after six years, often having nothing to show but debt.

College is not for everyone and never will be. But, on average, people without a college degree are likely to have lower earnings and less job satisfaction than those who successfully pursue a postsecondary education. There are also cultural and social benefits — studies show college education is associated with healthier lifestyles and a more involved citizenry — so college needs to be more accessible to more people, particularly those without the means for prep schools or private college advisers.

That means improvements in K-12 education, fixing the failing schools that send children into the world without the skills to succeed. It means increased support for public two- and four-year colleges and universities. It means paying attention to students once they make it to campus and giving them the educational and financial supports they need to stay there and graduate. And it means offering meaningful career training to young people who do not go to college.

As titillating as it might be to talk about how celebrities allegedly got their children into school, more attention needs to be paid to those who have been left out of the college conversation altogether.