I completed an executive MBA while working full time.
I chose it for personal reasons first, before money or career reasons. It is a huge workload, and I can't imagine an ivy league version being a fluffy walk in the park.
I am very glad I did, and it paid off in a large way, but I never would have gotten through if I was not personally vested. I was not able to contribute more than a basic work hour week, so did not grow at work much, until I completed, then BANG!
Warning...
I highly recommend NOT taking an MBA while working full time with two kids under 2 years of age at home.