What? A coin flip would still be 50% accurate. If 10% of startups succeed, and we say that heads is "succeed" and tails is "fail":

5% of startups will be predicted to succeed and will succeed (correct prediction)

5% of startups will be predicted to fail and will succeed (false prediction)

45% of startups will be predicted to succeed and will fail(false prediction)

45% of startups will be predicted to fail and will fail (true prediction)

50% true predictions, 50% false predictions. A coin flip is always 50% accurate.

A coinflip is always 50% accurate, no matter how improbable the event you're trying to predict. If I flip a coin to predict whether Cthulhu will rise tomorrow, I have a 50% chance of getting it right.