I'll reemphasize that even competent execution is rare; few people can execute perfectly on business AND technology AND marketing AND design AND .... Especially first-time entrepreneurs.
Fortunately, the other guy's deeply imperfect too. In capitalism, you just have to be better than the other guy. It's pretty hard -- the other guy has been at it for a while and you're just starting out, but it's far from impossible. Most businesses execute very poorly.
Fortunately, each time you try to execute, you get a little bit better at all of those, so after a few tries, you can out-execute. You also learn the advantages smaller, more agile players have over bigger ones.
I agree with the persistence bias argument 100%.