As others have alluded to...it’s a self selecting population. In my experience (business schools) a lot of ivy leaguers have an inherent competitiveness that they carry over from academia to business. I’ve worked with/for/managed great ivy grads and I’ve worked with/managed poor ivy grads...just like any other school. However, unless that person was gifted a legacy admission, they all had some internal drive to succeed.
Additionally one of the worst employees I ever had was a Wharton grad(MBA.) The worst kind of employee is one that drags their co-workers performance down and this person was the bow anchor of the titanic. One of those people that knew everything to the detriment of those around them and the overall business. Took me a year to get them “promoted” to a different division. Which to use a football analogy for people like the one I’m referencing, having an Ivy League degree can be a former 1st round pick that hasn’t quite lived up to expectations. There’s a team out there willing to take a shot on them turning it around. In my experience it will at a minimum get them through the application filters and usually an interview at the least.
Finally, I have a post-grad from GaTech and have earned 12 graduate credits from Harvard. Tech was way more challenging. Not completely apples to apples, but I still have nightmares about late/missing assignments at Tech.