The Greats that could have been

The other day I was thinking about riders like the Go-Show (Anthony Gobert). Riders who had all the potential in the world but for some reason threw it away. The Goshow was an amazing rider ( http://www.youtube.com/watch?v=eVZpoorKXOw just one of his rides) but got involved in drugs and threw it all away. He's not the only rider to do things like this, Vinales could have already done this with his hissy fit. So Reddit, I ask you, who do you think had the potential to be a world champ but due to their own mistake or a series of terrible luck coughHopkinscough meant that they were doomed to fade into obscurity to never be seen again...