I'm surprised anyone would think that 20% returns are over the top - outsized returns in markets are hardly an industry secret. Triple digit returns are not unheard of. Most of the people making big money don't exactly advertise and some are downright reclusive. But they certainly do exist.

I recommend reading http://www.amazon.com/The-New-Market-Wizards-Conversations/d... and the other versions in the series - I think there is 4 now. These are candid interviews with the individuals involved. They are good reading just for the interested entrepreneur.