My suspicion is most founders actually do have a pretty good idea of the answer on some level of consciousness, but avoid thinking about because it's terrifying.
I'd lay heavy odd the subconscious thought process goes along the lines of "If I'm default dead I have no idea how to fix it and so I feel powerless about it and that terrifies me and so I don't want to think about it and so I don't know the answer."
Not that that's exactly a successful strategy, but people don't always lock on successful strategies.
As a founder, I know all too well how easy it can be to ignore these potential issues. The funny thing is when you actually confront them and analyze your situation, you gain control. It's more relieving knowing than ignoring (because you never really ignore something like this without knowing you're doing it).
That's very strongly tied into personal responsibility, if you identify a problem and you tie it to your own performance you essentially look the problem in the eye and you say 'I can fix this'. If you ignore the problem or make yourself believe it is someone else's job or problem to fix this then you make it impossible for yourself to do something about it which hands control of your future to outsiders. The more problems you're willing to confront and analyze the bigger your chances of succeeding because all of those will be your problems and therefore very likely fixable.
Success is more random than your suggesting. IMO, the goal is to take risks that are in your favor. The less you know the harder this becomes.
If your default alive then you should consider being somewhat conservative. But, if your default dead then you need to risk something because your already losing.
The randomness of luck only comes into play when you've done everything else right, it's one huge 'AND' gate with luck as one of the factors. If you mess up on one of the others you're still dead no matter how lucky you were.
So by improving the rest of the gate functions the importance of the luck element goes up because it may be at some point the only item between you and success and then if it swings your way you're suddenly doing very well.
See also: the myth of the overnight success. All that is is a ton of preparatory work and one opportunity properly seized.
The calculation isn't that simple to calculate, it really requires a spreadsheet or calculus, you can't in general calculate it in your head. A simple heuristic is "is my runway going down or up", it is conservative.
I'd lay heavy odd the subconscious thought process goes along the lines of "If I'm default dead I have no idea how to fix it and so I feel powerless about it and that terrifies me and so I don't want to think about it and so I don't know the answer."
Not that that's exactly a successful strategy, but people don't always lock on successful strategies.