Don't worry so much about whether you will actually make money, to keep it a hobby, but make it in such a way that you might, to keep alive hopes of actually making a living out of it.
Doing it that way will allow you to make it however you please and to make it as beautiful as you want. The fun part is that along the way you will encounter critical areas you never thought about, but which are quite interesting to do once (setting up a build infrastructure, migration etc.)
Just make sure your code stays a thing of beauty, something so solidly engineered that you're truly proud of it. Don't rush things but take the time to make them 'just right'.
That way you'll have had a great time writing it, and if your company ever gets off the ground you'll have an amazing code base to start off with.