The person with income 4 years earlier as higher potential investment income, which is ignored because this is "earnings" not net worth. I don't think I've ever seen one of these analyses factor that in.

I'm making the calculations as simple as I can to explain why college might not be being taken up, given the lack of real profit off of the investment.

In the other direction, this is assuming that no one has any kind of income while attending college.

We could add that in, but we're still talking quite small amounts. $10k-$15k a year I suppose.