Every project, company, contributor, and community get to decide this for themselves. There are no easy or correct answers
On the monetization question - do you need to give others the opportunity to give money back? If so, who should assess the size and "adequacy" of these contributions? If you don't provide the opportunity for others to sponsor the project, does it change your rights and obligations?
These are not easy questions, and now our entire industry is trying to work out the answers. OP's is one voice in this discussion, and an important one given GitLab's prominence and the fact that they took a different path, which seems to be working well for them.
It's also a way more complex problem for software like Terraform that explicitly depends on the work of others for its core functionality than for something that works perfectly fine standalone, like Hashi's Vault, or indeed GitLab itself.
If this is somehow permissible under the original license, it points to needing licenses that offer more consistency and protection. If I contribute to your project, I want to make sure that you can’t close the door on the codebase whenever you feel that you’ve harvested enough value from me, value that you’re now going to go monetize with others.