It seems that the author is proposing to take an equal portion from all college attendees seeking financial help as a percentage of future earnings above a certain baseline. In other words, if the baseline is $40k and I agreed to pay 10% above that for 15 years, then after attending college and making $60k per year for the next 15 years, I would pay out $2k per year over 15 years.
However, if I make $35k, I don't pay anything.
This is very different than what you are describing, which amounts to a progressive tax on the more successful students. If anything, it would be fair to put some sort of a max on the amount of income that could be counted. For example, if I'm expected to make $60k, but end up making $6 million due to some luck or whatever, it doesn't seem entirely fair to attribute 10% of that to just education...
I could see varying the % required by the "investor" based on some sort of merit-related valuation process, where the individuals most likely to be worth the investment are given a discount.
That "unfairness" is pretty inherent to the equity-style model in any area. I mean, you give someone 5% equity due to their role as an early employee, and your company quickly gets bought out for $500m due to some stroke of good fortune; is it really "fair" to attribute 5% of that to just this one employee? Probably not, but that's how equity-based models work.
If anything, equity at scale relies on outsized profits from a few big winners, which is why VCs play the probabilities by funding a bunch of fences-swinging startups. Perhaps university funding would be similar? Of course, if someone is sure they're going to get rich, they wouldn't sign on to giving a university a percentage of future income. But a lot of people who eventually got rich had no idea, at the time of going to college, that it was likely they would. Similar situation as startups, really: if you knew that you were a shoo-in for a multibillion IPO in the near future, you wouldn't give away nearly the equity that you normally do in venture rounds.
It doesn't really seem any more unfair to me that universities would get outsized profits from their equity share in a few big winners, than the same situation with venture capitalists getting outsized profits from their few big winners. In retrospect, you can always say that less than 10% of John Smith's success came from his university; but in retrospect, you can always say that less than 10% of a particular startup's success came from a particular Series A backer.
However, if I make $35k, I don't pay anything.
This is very different than what you are describing, which amounts to a progressive tax on the more successful students. If anything, it would be fair to put some sort of a max on the amount of income that could be counted. For example, if I'm expected to make $60k, but end up making $6 million due to some luck or whatever, it doesn't seem entirely fair to attribute 10% of that to just education...
I could see varying the % required by the "investor" based on some sort of merit-related valuation process, where the individuals most likely to be worth the investment are given a discount.