Here is a story. It happened to the eldest brother-in-law of the cousin of a friend of mine’s colleague at work. His name was, and still is, Patrick.
Patrick was a computer scientist with a PhD in advanced network topologies. He spent two years and his savings building a new product, and chose the BSD license because he believed that would get him more adoption. He worked in his attic, at great personal cost, and proudly published his work. People applauded, for it was truly fantastic, and his mailing lists were soon abuzz with activity and patches and happy chatter. Many companies told him how they were saving millions using his work. Some of them even paid him for consultancy and training. He was invited to speak at conferences and started collecting badges with his name on them. He started a small business, hired a friend to work with him, and dreamed of making it big.
Then one day, someone pointed him to a new project, GPL-licensed, which had forked his work and was improving on it. He was irritated and upset, and asked how people—fellow open sourcers, no less!—would so shamelessly steal his code. There were long arguments on the list about whether it was even legal to relicense the BSD code as GPL code. Turned out, it was. He tried to ignore the new project, but then he soon realized that new patches coming from that project couldn’t even be merged back into his work!
Worse, the GPL project got popular and some of his core contributors made first small, and then larger ...