Regarding your last point: nothing is a sure thing. Of course survivorship bias is a thing. Of course believing in yourself/ability to figure stuff out isn't a sufficient condition for success. But, maybe it's just a necessary one?
On the last point: Of course nothing is a sure thing, and not once has success come from "believing in yourself" trumped "talent and hard work" without straight up dumb luck. Whether starting a business, playing the lottery, or testing gravity by way of jumping off a large building, I think "believing in yourself" is flat out useless. Or, in a different way of phrasing it, "believing in yourself" is about as fundamental to entrepeneurship as waking up and getting out of bed - of course it's necessary, but that doesn't make the "you can do it too!" framing any less vapid.
It wasn't dumb luck or short cuts, it was smartly planned strategy. It was Agile if you want to get cute with it.