Do adults really need 7-9 hours of sleep a night? Nature wouldn't require us to be in a such compromised situation if we are to survive. Any sleep studies on healthy humans eating optimal human diet (ie, whole foods meat based)? I am doing quite well on 5-6hrs of sleep/night.
There's an asymmetry in predictions.
Bad predictions are mostly forgotten. The one who made the prediction has little incentive to remember and most aren't paying attention.
Good predictions are usually remembered. The one who made the prediction brags about it.