Godot’s MIT license certainly let’s you redistribute the engine as part of your proprietary game. However, it equally lets others redistribute their games under the same open source license, or even a copyleft license. So it’s spirit seems equally business, hobbyists or free software moralist.

Copyleft helps me by making sure my code can’t be included in a proprietary software. My code is there to be copied but if you make changes and redistrubte them then I get access to those changes. Maybe I use them in my software, thus improving it.

The purpose of copyleft is to ensure the freedoms and restrictions made by a license are enforced by copies/forks/derivatives.

Best to talk to people interested in contributing to see what they would think?

Finishing a project is difficult (imo) so good job! 👍