> Strange how I never see this line deployed against the mortgage interest deduction or health care for wealthy retirees

For what it's worth, I see arguments like this all the time. Might just be the corner of the information ecosystem you hang out in.

> Subsidizing college education, at least, has a reliably positive ROI.

Maybe it did in the past, where the greatest marginal gains were. Does it still hold true now? Over a third of the US has a bachelor's degree. Is there a reliably positive ROI to society in taking that third to, say, half?