In 1878 Alexander Graham Bell offered to sell his invention of the Telephone to Western Union, the largest telegraph provider of his day for $100,000 ($2.42 million in current dollars). Based on a report from their internal committee they refused the offer:

"The Telephone purports to transmit the speaking voice over telegraph wires. We found that the voice is very weak and indistinct, and grows even weaker when long wires are used between the transmitter and receiver. Technically, we do not see that this device will be ever capable of sending recognizable speech over a distance of several miles.

Messer Hubbard and Bell want to install one of their “telephone devices” in every city. The idea is idiotic on the face of it. Furthermore, why would any person want to use this ungainly and impractical device when he can send a messenger to the telegraph office and have a clear written message sent to any large city in the United States?

The electricians of our company have developed all the significant improvements in the telegraph art to date, and we see no reason why a group of outsiders, with extravagant and impractical ideas, should be entertained, when they have not the slightest idea of the true problems involved. Mr. G.G. Hubbard’s fanciful predictions, while they sound rosy, are based on wild-eyed imagination and lack of understanding of the technical and economic facts of the situation, and a posture of ignoring the obvious limitations of his device, which is hardly more than a toy …

In view of these facts, we feel that Mr. G.G. Hubbard’s request for $100,000 of the sale of this patent is utterly unreasonable, since this device is inherently of no use to us. We do not recommend its purchase."

Ben Horowitz comments: 

"What mistake did all these very smart men make in common? They focused on what the technology could not do at the time rather than what it could do and might be able to do in the future. This is the most common mistake that naysayers make. 

Who does the Can’t-Do Culture hurt the most? Ironically, it hurts the haters. The people who focus on what’s wrong with an idea or a company will be the ones too fearful to try something that other people find stupid. They will be too jealous to learn from the great innovators. They will be too pigheaded to discover the brilliant young engineer who changes the world before she does. They will be too cynical to inspire anybody to do anything great. They will be the ones who history ridicules."

From Ben Horowitz original article: Can-Do vs. Can't Do Culture