Building a great company is about predicting the future. You build something people want now and predict they'll continue to want it in the future.
There's something Garry Tan sometimes says: he starts a sentence with "if you live in the future…" and completes it with a prediction about how the future will look.
Things that seem unlikely to happen tomorrow, but could happen years from now, start to seem plausible.
Steve Jobs might have said, if you live in the future, the file system will be less important. He built iOS devices to not have a central file system. 
Drew Houston might have said, if you live in the future, you will have a file system that's accessible anywhere, from every device. He built Dropbox.
Elon Musk might have said, if you live in the future, cars will be electric. He built Tesla.
Dean Kamen might have said, if you live in the future, you won't drive short distances. He built Segway.
Bill Gates might have said, if you live in the future, there will be a computer on every desk. He built Microsoft.
While seemingly simple statements, they produce high stakes decisions. You bet your company or product on it. It creates focus.
I think the minimum viable product has made us so effective at thinking short term that we spend less time thinking long term. We talk to customers and iterate daily. But, we may forget about this future world in which our products exist.
Before you build, it's worth making a guess about the future, even if it seems obvious. Don't think about switching costs, moats and other barriers to entry. Just think, if you live in the future, what does it look like? When you see it, that's what you should build.
Comments on Hacker News: https://news.ycombinator.com/item?id=5799838
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 Steve Jobs discussing the file system in 2005: