Once you play with a fax machine for the first time, an early adopter can see that such a tool would be useful amongst the population. The network effect dictates that the more people that used fax machines, the better it was.
In Back to the Future Part II, which was filmed in 1989, they predicted that the fax machine would be an important tool of communication. That every household would have 4 or 5 of these things. Now, most fax machines are confined to an office and are practically obsolete.
While we might be good at predicting something at first, we have a hard predicting the application of something in the long run.