I've been feeling a lot the same way, but removing your source code from the world does not feel like a constructive solution either.

Some Shareware used to be individually licensed with the name of the licensee prominently visible, so if you had got an illegal copy you'd be able to see whose licensed copy it was that had been copied.

I wonder if something based on that idea of personal responsibility for your copy could be adopted to source code. If you wanted to contribute to a piece of software, you could ask a contributor and then get a personally licensed copy of the source code with your name in every source file... but I don't know where to take it from there. Has there ever been some system similar to something like that that one could take inspiration from?