He had a revelation in 1945 of a future with real-time interaction with computers on screens. It would take 23 years before he could present a Hello World version, and even this was slightly too early for mass production. Everything we are doing right now goes back to this one man's fanning a flame.
The best write-up available online, and one that inspired me deeply never to give up, is The Loneliness of a Long-Distance Thinker, chapter nine of Howard Rheingold's excellent Tools for Thought. If you have a half-hour or so, please give this a read.
I worry we have stopped envisioning the distant future. We are far too busy fighting off the people that revel in ignorance, think Armageddon will be Tuesday and therefore there is no reason to build or even repair the big projects of the modern world. We need our dreamers, so perhaps this loss is our call to become the dreamers and builders in spite of the naysayers.