"If we spend a second thinking about this, if 9 out of 10 startups fail, then we only need to roll the dice 10 times and the last startup will (by statistics) achieve success." That is not how statistics works. : With a 90% failure rate, your chance of failing 10 times in a row is (9/10)^10 ~= 35%.
They're also not independent trials. If you just failed 9 times in a row, you're probably not the best at startups.
Helps to explain how there are so many 'anomalous' serial-entrepreneurs :)