Companies could take your discoveries and sell things based on your work before LLMs ever existed. What's changed?

There was a level of patent/copyright protection, there was a level of awareness of stealing, a company could be taken to a court of law. A writer of a PhD thesis could show that someone lifted huge parts of a dissertation without attribution. All that is gone.

They could, but I could always hope they wouldn't, and most of the time I wouldn't be disappointed. AI companies don't even have means to attribute to someone the solution they're selling.