1) We didn't spend a lot of time building something nobody wanted (which is the main theme of this post).
2) We experimented a lot with our product design because we knew we'd be getting feedback quickly and thus could take interesting risks. There was little "analysis paralysis".
Assuming you are your own target customer (in that you would actually pay money for what you're building) I think it can be too easy to conflate what you want to build ("this is fun/interesting") with what you want ("I need this and am willing part with money to get it").
This thread is a great reminder, so thanks.