3) The simple theory of random stupidity strongly predicts a random pattern of overspending on some things, and underspending on others. In terms of statistical inference, such a theory is relatively easily beat by any other theories that can explain patterns in over and underspending in any other terms. Yes, you might try to retreat to a correlated-randomness theory, which posits that over versus underspending is correlated in “related” areas. But then you’ll need a theory of “relatedness” of areas.
We also seem to see overspending in medicine, law, school, investment analysis, campaign spending, and much else. A consistent pattern I think I see is overspending in areas where spending lets one associate with prestigious folks. So I suggest that much of this overspending is better explained via motives to gain prestige via association.