Here's a 2008 article by Paul Buchheit making several excellent points:
You can take the smartest, most experienced, most connected, most brilliant people in the world and have them build the most stunningly designed and technically advanced product in the world, but if people don't want it, then you will fail.
Even if you aren't the smartest person around, and your product is kind of ugly and broken, you can still be very successful, if you just build the right product.
Where "the right product" is a combination of your product idea, paying close attention to what the market is telling you, and having a market that's worth serving.
The key take-away is summarised near the end of the article:
So what's the right attitude? Humility. It doesn't matter how smart and successful and qualified you are, you simply don't know what you're doing. The good news is that nobody else does either, though some are foolish enough to think that they do (and that's why you can beat them).
What is the humble approach to product design? Pay attention. Notice which things are working and which aren't. Experiment and iterate. Question your assumptions. Remember that you are wrong about a lot of things. Watch for the signals. Lose your technical and design snobbery. Whatever works, works.
If you hadn't yet read this post when, go read it now.
If you read this far, you should get more similar articles by email.