As with earthquakes, successful start ups are notoriously hard to predict. We should be thankful that VC invest so "broadly". In the same vein, where a founder has previously worked should be viewed as just a luck indicator rather than a predictor.
I don’t think that first-timers ignore the amount of work that much, but simply having an idea beforehand helps. Knowing what it’s like to change yourself is also a very difficult thing to anticipate.