What would she do if she had it? “What I’d want to do in general is provide what I know works,” she said. “One thing I know that works is great teaching. A teacher connecting and really understanding these students’ lives is the gold standard.

“The second piece would be to dramatically increase advisers — advisers are both adults that I would employ and peers,” she continued. “Peers who would tell a student who got a C and wanted to drop out, ‘No, no, you have to stay!’ I’d want to stabilize the students’ home lives. I’d want to make sure they had child care, that they knew how to pay the rent, that they weren’t working 80 hours a week and going to school.”

In the meantime, LaGuardia has devised some of its own solutions. One of them is called the Pushy Moms Club. Observing her friends uptown, Ms. Dubinsky realized that many had children who now required less of their time, but the mothers themselves were still running on surplus energy from years of meeting the obligations that the obsessive culture of modern parenting imposes. At LaGuardia there were many students with absent parents, so she paired up the women and the students, to get through the complicated process of college transfer admissions.

One friend, Joyce Siegel, met with a young woman who aspires to be a gynecologist. She was having a hard time wading through schools with good pre-med programs. “Joyce walked her over to the Barnes & Noble, where they got a Barron’s guide and started to make a list of schools that fit her criteria,” Ms. Dubinsky said. “Every family of a child in private school in New York owns at least four college guides.”

Across sectors of education and social service, philanthropy cannot replace the impact of considered government investment. But it can alter individual lives in unforeseeable ways. At Mr. Akdemir’s dinner two weeks ago, a Chinese student, Yifei Shen, who had recently completed his coursework at LaGuardia and enrolled at the School of General Studies at Columbia, was seated next to Mr. Selz. Mr. Shen talked about the way his $4,000 LaGuardia scholarship helped him. Before receiving the money, he said, every day at 3 p.m. he would start thinking about a hamburger. But he knew that if he ate a hamburger at that moment he would not have money later, if he found himself hungry again. The anxiety and constant dialogue in his head about whether or not to succumb were exhausting all of his mental energy, he said.

Afterward, he ate when he wanted.