Businesses have been run well without MBAs for millennia. The merchants of Carthage did not need them. Kanye West does not have one. That said, an MBA will get you up to speed on business in a general sense. But so will a good book, for far less money and time.
The MBA is a club like any other: you are either in or out, that is its main selling point. Incompetent people will get in, and they’ll leave incompetent. But they will beat non-MBAs at job interviews because they had the money to attend a prestigious school and scraped through on Cs. You will not leave business school with the next Google, YouTube or Twitter in your head; if it is to happen, it will happen anyway. Reading case studies about Steve Jobs is not enough for you to become like him. To start something takes imagination and courage.