1. Makes research a lot easier.
  2. The fact that you already know something about a particular subject matter is a strong indication that your new project will be more fun than work.
  3. It will increase the probability of success.
  4. The final product will be easier to promote because you most likely already have a circle of friends who share this common interest.
  5. This circle will serve as an automatic support system which is an essential source of motivation.