I've been told for decades that a college diploma is worth a million dollars more in income over a working lifetime compared with not having a degree. I have no idea if that applies today, or which way the number may have moved over the years. Paying at say, 25% on that income would net the government an extra $250,000 over their lifetime, no?
So it seems to me that free state tuition pays for itself at least if not pays with interest. & as a bonus, you get an educated citizenry - which has no downside as far as I'm concerned.
Free state school college is not a giveaway. It is the best investment we can make in our future & pays for itself.