HYPSM = the schools with the largest endowments.
Which private university has the 6th largest endowment ?
Plus, as noted above, an added “C” to “HYPSM” would just confuse the populace about whether the “C” represents Chicago, CalTech, or Columbia. Not worth the headache. Better to just add “P” for Penn, “D” for Duke, or “N” for Northwestern. Let’s face it, until Columbia changes its name, it’s not a real candidate for inclusion.
P.S. Plus, shouldn’t we reserve the next spot for a school that begins with a vowel ?