Quick background: product marketing, went to a T15 MBA mid-career (5 YOE going in). came back to PMM at a bigger company, basically the same job title but at higher seniority.
the ROI story people tell you: 'the MBA unlocks the VP track.' maybe. kind of. what it actually unlocked for me was the ability to have conversations with CFOs and GMs without feeling like I was faking it. i understand P&Ls now. i can sit in a QBR and follow the revenue model. that's worth something even if nobody gives you a gold star for it.
also: the network is real but not in the way I expected. it's not that alumni open doors (some do). it's that you have a cohort of ~300 people you went through something hard with, and over a 10-year horizon, some of them end up in rooms you want to be in. it's slow. plant-the-seed stuff.
what I did NOT get: a massive salary jump on day 1. the first post-MBA job paid about 20% more than what I was making. i was hoping for more. it normalized over a few years but the immediate payoff wasn't what the program's employment report implied.