Investors bank on most of their investments not succeeding, and the few that do making up for the rest.
The truth is, nobody knows how to bottle "success" and reproduce it -- but in a sense that's what management school is trying to do. With just the right management approach, applied in just the right ways, you can get Instagram instead of Color, or Google instead of Cuil.
The problem is that it's very easy to look at the failures and pick apart the problems. But it's very hard to look at the 1% that succeeds and figure out why -- and when it's attempted it usually overlooks the cases where the company succeeded despite having many of the problems the failed companies had.
Most companies succeed because of 90% dumb luck and 10% business strategy.
(hell, business is so screwed up people still don't understand how to define success. You see it here all the time that a "successful" startup is one that raises a huge round, not one that's profitable and growing...even BusinessWeek does this)
Early stage startup investors expect most investments to fail. Those investing in mature companies expect their investments to do well over many years.
I'm sure MBAs have plenty of stories of incredibly inefficient companies that have squandered opportunities. MBAs aren't about growing startups, they're about taking the now $1bn Instagram and doing more with it.