I write a great new song, perform it a few times while I'm working out the kinks, saving up for studio time, etc. Before I know it, a large media conglomerate has used their performance scouts, on-staff musicians, and fully tricked out in-house studios to steal my song and release it nationally... before mine is even done. I have no legal recourse and, even if I do ultimately release my version, it's forever seen as the cover version.. and that big conglomerate makes a huge pile of money on my work, without me getting a dime.
Sure, that sucks, but your problems didn't start when your song got "stolen", they started when you decided your business model would be to peddle a string of ones and zeroes. While you wouldn't have legal recourse in your scenario, it's not like you are completely helpless in that situation either. A lot of people who bought the hit from the media conglomerate would throw their support to you if they found out you were the original composer. After all, the people who would buy a song (when they could just as easily get it for free since there is no copyright) are the people who are looking to support the creators.
Thus spake the master programmer: "After three days without programming, life becomes meaningless." -- Geoffrey James, "The Tao of Programming"