Its not clear from the article which factor the 50% figure applies. I doubt its the overall odds ratio, but rather the likelihood given some priors. For example, given a prior that 90% of startups fail, what is the likelihood that this particular startup will succeed? If the prior is already factored in, then the model predicts no better than a coin flip.

The point made in the article is that investing at the odds of a coin flip would be better than investing with incorrect risk assumptions (ie. buying into "particularly bad ideas").

I stand corrected, you're right. I'm supposed to know better.