I don't agree that a significant amount of low income people who can't afford college are having that financial problem because they live excessively beyond their means. I also suspect the reason a lot of lower income people are working full time jobs is just as much for health insurance as the actual paychecks.
What if University was free _AND_ health care & small apartments were supplied for those(and family) who qualify for excessive hardship and maintain high GPA?
Anything to raise the average education level of the population I think is a win, even if it has to come from the higher-income taxpayers... as long as data shows that indeed significantly more people end up with degrees.