I know if a person started boxing at the age of 20 he could easily contend, win titles, and make good money. If you start at that age, can you be in a world all of your own such as Ali, Robinson, Jones, Mayweather? This of course is assuming you have their same natural ability and understanding of the art, but you happend to not start at a young age. Or is it absolutely necessary to have a long, drawn-out amateur career (5-10 years) to be able to perform like that.