This sentiment completely bulldozes over nuance. Not all predictions are created equally, a person that is today predicting a mass market for self driving cars

This sentiment completely bulldozes over nuance. Not all predictions are created equally, a person that is today predicting a mass market for self driving cars is not the same as a person predicting a mass market for flying cars. It's not pessimism to dismiss the absurd. Of course, vision is necessary for progress, but only a tiny fraction of the so-called "optimists" actually "make money", most of them fail.