Here is a link to a collection of predictions and statements that proved spectacularly wrong.
Some of my favorites:
"The horse is here to stay, but the automobile is only a novelty—a fad."
- Advice from a president of the Michigan Savings Bank to Henry Ford's lawyer Horace Rackham. Rackham ignored the advice and invested $5000 in Ford stock, selling it later for $12.5 million.
"That the automobile has practically reached the limit of its development is suggested by the fact that during the past year no improvements of a radical nature have been introduced."
- Scientific American, Jan. 2, 1909.
"Automobiles will start to decline almost as soon as the last shot is fired in World War II. The name of Igor Sikorsky will be as well known as Henry Ford's, for his helicopter will all but replace the horseless carriage as the new means of popular transportation. Instead of a car in every garage, there will be a helicopter.... These 'copters' will be so safe and will cost so little to produce that small models will be made for teenage youngsters. These tiny 'copters, when school lets out, will fill the sky as the bicycles of our youth filled the prewar roads."
- Harry Bruno, aviation publicist, 1943.
And one for railroads:
"In Bavaria the Royal College of Doctors, having been consulted, declared that railroads, if they were constructed, would cause the greatest deterioration in the health of the public, because such rapid movement would cause brain trouble among travelers, and vertigo among those who looked at moving trains. For this last reason it was recommended that all tracks be enclosed by high board fences raised above the height of the cars and engines.
Rail travel at high speed is not possible because passengers, unable to breathe, would die of asphyxia."
- Dr. Dionysus Lardner (1793-1859), Professor of Natural Philosophy and Astronomy at University College, London.