No one launches with a perfect product. If it's novel and popular then you have to expect others will attempt to piggyback your success, at which point the quality of your team and the deep knowledge of your customers will be vital.

You will have the best usage data and the best access to what is good/bad about your existing proposition via existing users. This will allow you to make smart decisions about the cuts/additions to make to your product, enabling you to stay ahead of the game by delighting existing users and keeping your position as the leading experience in the space.