It's all about the $$$ and the community. Blender started as a commercial project too. I was already using it in the 90's alongside POVRay.

The good thing is unlike in the photography or the print industry there is no real industry wide vendor lock-in when it comes to formats in 3D, so it's always possible to create a challenger.

Right now Godot isn't really on par with Unity, but it could become the de-facto game engine for Blender in the future if Godot allows deep integration with the former.