I guess your real question is why she wasn’t accepted to Harvard or Yale, but only to a lower Ivy like Columbia. Could it be due to her father’s background?
My take is that it would not have anything to do with the deadbeat father or his financial situation. If anything, the low income status would have helped her at H/Y. It is just that the competition at the very top is so fierce that even a low income/QB status hook was not enough. And you never know what hooks others at her schools really had. At the national level there are many FGLI kids with 1550+ and national/int awards applying to H/Y, and not all are accepted.