This behavior is antisocial, and completely destroys the offering/concept for everyone.
I have a bootstrapped software company with an open-core product. Meanwhile, a VC-backed startup that has raised over $100m of funding decided to use one of my core open source libraries (which they haven't contributed to in any way) for a critical component of their commercial product, which also overlaps with my product's functionality in some ways.
In response, I eventually made the difficult decision to archive that library's repo and moved its functionality into my main product in a way that prevented external use. So then this startup created a hostile fork of my library, and started to implement functionality that is only present in my own commercial product.
After that, I had to waste several months of unpaid time just to make their fork of my own library no longer easily compatible with recent versions of my own product. Some time later, finally the startup decided to abandon use of my library altogether and wrote their own similar library (which was undoubtedly much easier for them, being able to see all the edge cases my library already handled).
My lesson from all this: I will never create another new large open source product ever again. Too many sociopaths out there for the system to work at all. If I ever decide to make something source-available, I will consider BSL.
And before someone says "why not AGPL?", it is because many companies don't touch AGPL software with a ten-foot pole. My sense is that adopting AGPL for a brand new product typically causes the product to be dead on arrival. That said, I would honestly love to be wrong here.
If there are a lot of AGPL open core / commercial FOSS companies that have been successful, please share examples, I say this genuinely and without snark.
