I lost nearly $13M in equity. I got $0, plus I spent most of what I had at the time trying to pursue it legally. Basically, my business partner (who was already very wealthy before we started the company) and I had a personal falling out (believe it or not, over a woman). He decided that since he had financed everything, that it was his. He pushed me out, but I still had my equity.

It turns out, however, that the moment I was out he transferred all of the company's IP to a different corporate entity that he owned 100℅ of (same exact company name, just a different structure). He eventually sold that entity. The only thing he couldn't erase was my name being on the patents, but apparently the acquiring company never bothered asking who I was. But in the end it didn't matter, I simply didn't have enough resources to see it all the way through.