"I want to be an executive" is a pretty fucking lame vision, as it were. I'd rather be around people who have concrete ideas of what they want to build, and who'll lead when appropriate and follow when appropriate. People who say, "I'm a leader" but don't have a good sense of where they want to lead, are annoying. What they're really saying is, "I think that, based on some linear combination of pre-existing socioeconomic resources and inflated self-image, I have the right to a job where I tell other people what to do."
I don't think that all MBAs are douchebags. I know plenty whom I like a lot. Unfortunately, the culture of business school and especially the elite business schools is one of entitlement and position-seeking. When that type of person founds a startup, you get a lot of the same toxic big-company behaviors and formalities and political structures, but in a small company that can't afford the inefficiencies. Now you have the worst of both worlds between small companies and big ones, and a high likelihood of failure or, if the connections are there, Knewton-esque mediocrity.
Oddly enough, if I had a child I'd recommend that he go to the highest-ranking business school out there. Harvard is going to open doors that are just ridiculous, whereas the #20 school is probably educationally equivalent, but isn't going to make you a CEO at 30. On the other hand, if I were hiring, I'd be extremely skeptical of the Harvard MBA and less skeptical of the Booth MBA and even less skeptical of the UWash MBA. In most educational divisions, the correlation between prestige and douchebaggery is nonexistent, i.e. Yale law students aren't noticeably douchier, or less douchey, than students at middling schools; in MBA school, it's clearly a positive correlation (although Stanford is probably worse than Harvard, though less prestigious, for obvious reasons).