My hunch is that it doesn't happen. Most people who are self taught are at least honest enough with themselves that they understand that when they go into a tournament full of 100+ people who really train that they will be promptly squashed and verbally assaulted for putting themselves and others at risk when they fight not knowing what the heck is going on. They may verbally defend their "training" on forums and the internet, but I've never seen one with the balls to go to a tournament to test their own "training" in reality. Deep down they know their training routine isn't quite legit.