When Jane Sanders was in charge of a small private college in Vermont for seven years, it sank deep into debt while trying to expand its campus. Many students took out tens of thousands of dollars in loans to attend, but their investment was questionable: Only a third of degree holders from Burlington College earn more than the average person with a high school diploma.Jane Sanders’ husband, presidential candidate Bernie Sanders, has offered a higher-education plan that would make tuition at public colleges free.