As long as you don't earn 100.000,- $ in a year, Unity is free too. And if I would earn 100.000,- $ a year with my games, I will pay the price with ease!
Another problem: Godot don't support exporting to consoles like the Nintendo Switch - this would only be possible with the help of third party developers and I suggest that this would cost money too.
So the mighty export feature of Unity AND the great documentation/ tutorials/GoogleHelp were the main reason driving me to Unity. Until now I'm very satisfied with it.