Because you build an awesome product for free doesn't mean it's going to be successful.
I've learned it the hard way! I've created many Open Source side projects and you know what? They all miserably failed.
It's really hard to sell something you loved to build. But try to sell it, at least $1! You're going to be surprised.
The main reason is simple: if you make $1, you'll get that extra motivation boost you needed to improve your product 🚀
The second reason: you will get confident about selling your next product! And who knows? Maybe makes a living with it!