My own anecdata: the (also two) ex-McKinsey people I've known seemed reasonably decent people at heart, but both possessed a toxic combination of:
(1) being absolutely intoxicated by their own old-money-fueled prestige academic/career path, which gave them a
(2) vastly overrated sense of their own knowledge, ability, wisdom, capability, importance, and general superiority to anyone not in possession of these stellar academic/prestige institutional credentials which was
(3) completely unfounded in every way.
I'm no longer impressed by Ivy League or any of these prestige institutional credentials.
(1) being absolutely intoxicated by their own old-money-fueled prestige academic/career path, which gave them a
(2) vastly overrated sense of their own knowledge, ability, wisdom, capability, importance, and general superiority to anyone not in possession of these stellar academic/prestige institutional credentials which was
(3) completely unfounded in every way.
I'm no longer impressed by Ivy League or any of these prestige institutional credentials.