A large portion of MBA’s – particularly at some of the highest ranked schools – get their MBA so that they can more easily advance at whatever company/firm they are currently working at (i.e., if they are in consulting, etc.).
I read a report recently that only 4% of MBA applicants go to business school because they aspire to be entrepreneurs, although a higher proportion do, in fact, become entrepreneurs after getting their MBA.
Generally, MBAs tend to pursue higher-responsibility, managerial roles at large corporations, or take jobs in consulting/finance etc.
I’m sure there are plenty of people who don’t fall into this categorization, but this is certainly a trend among many MBA recipients.