As I finished my case study sketch in OneLargeEvolutionaryAttempt I began to think about the reasons of the "super-manager" there in choosing WaterFall to the detriment of his own project and how they fitted with the four options I've posited on Wiki, IgnoranceFearPrideOrFraud.
Simplifying only a little the results came out as follows:
This mix (or something better) is very common I'm sure. But if you dare even to mention the "extreme" possibility of Fraud as a factor in commercial choices, I think people hear you as saying "it's pretty much the only factor" or "by far the most important factor". In IgnoranceFearPrideOrFraud I wasn't asserting that, I was genuinely trying to ask the question of what mix people had experienced. I just couldn't possibly in good conscience have left fraud out completely.
Here's a parallel example:
I don't know (and nor do you) what is going to happen as a result of Y2K system failures starting (wrong but give me some slack here) in nine days time. The probabilities as I see it are (for illustrative purposes only):
Because MostExtremeIsHeardLoudest.
Now perhaps I understand.