I don't find it is so important that people like Jobs, Gates, Brin, etc. have sometimes correctly predicted the future. What is important is that they executed, and turned these predictions to reality. Even more. They turned these predictions to everyday reality for most people, instead of a select few.
It annoys me when these people are compared to people who just throw a million ideas around and then, when one of these ideas becomes reality, they claim that they are so good at predicting the future.
Kay popularized that quote, but didn't invent it. It goes back to a 1963 book called Inventing the Future by physicist Dennis Gabor: http://quoteinvestigator.com/2012/09/27/invent-the-future/
Gates on the other hand was a big believer in market research and focus groups. I think that's why he was so into pen computing. He was unable to get past the windowing, desktop, pointing device paradigm.
Rather I think what happens is that some technology matures, and then some people that are familiar with that technology are able to recognize that it can be made into a real product that has market potential.
These people don't need market research, because from their standpoint, with their knowledge, it's "obvious". Eg. if you knew about the internet and email in the 80s, it would be obvious that it would replace telex at some point, even though you might be off with the timing of that transition.
That's the reason of why, when they speak, sometimes the things they tell may seem to be a little bit odd at the time, but eventually that things became real.
There are a few examples of this in the interview made by AllThingsD to Gates and Jobs together in 2007. [1] At 35:30 Gates said that he was sure the tablet market was about to explode (while jobs was looking at him with a funny poker face), and later, he basically described Kinnect, a few years before Project Natal was made public.
If Google haven't revealed Glass or their autonomous cars, and Larry or Sergey came out speaking about driver-less cars, and wearable devices, some would think that they are dreaming, but the truth is that they are describing their vision, and they are working to make it real.
It's like what jobs said at min 43, when asked about 5 years from 2007 (yeah, right now!). And he said: "I don't know, " [...] "but something comes along, gets really popular, people love it, get used to it, you want it on there".
They are not wizards, they happen to know what currently exists, and what's being developed. So, instead of making weird assumptions (like: "ok, assuming that we will develop a material 1000 times stronger, 100 times lighter and 10 times cheaper, we'll have X in ten years"), they rationalize about what's the logical evolution of the technology, based on what they know.
[1] http://allthingsd.com/video/?video_id=60C4F9FA-9AD5-4D04-8BB... , Min 28 and forward.