Don't you have to start off as an ameteur though?
Nah you don't have to, plenty have gone straight into the Pro ranks with no Amateur background at all and gone far e.g Dwight Qawi and Barney Ross.
When amateur boxing was basically a 3 round pro fight.
And people wonder why Old Timers talk about the Good Old Days...and why boxers back in the day were better prepared to go from amateurs to pro. Amongst other things.