Fire and forget
These days there are so many startups with new sites that I find it hard to believe that many of them will be around for the long term. People have only so much time to spend online, and they're not going to split it too many ways. (The Attention Economy.)
The problem of attracting users' time can be eliminated by creating a product that helps users without needing their time. Or, to be more accurate, needing only enough time for them to start up the product, registering and setting preferences etc., after which they only need to go back if they want to adjust something. "Fire and forget" (a military term that's proven useful elsewhere).
You might want to keep this in mind if you're thinking of putting together a startup.