the first rule of passive income is you don't talk about passive income... (cuz someone will copy it and end the gravy train)
It's virtually impossible for one to prevent competition
If your business idea is so fragile that can be blown away by competition, you might want to rethink your strategy.
It may not be that you "want to rethink your strategy," but if you stumbled into becoming a one man show for a super niche unrivaled business app, why talk about that on a forum of developers?