My great uncle was a street fighter who went straight to boxing professionally after having no experience in amateur. However, unfortunately the nerves got to him and he retired after only 4 fights and a record of 1(1)-3(2)-0 He was a very good boxer though and people had extremely high hopes for him..Just happened that he was no good under pressure, shame.
My brother in Law hector colon was a 7 time US National Champion. Best in his weight class all those years and had an absurd knock out ratio in the amateurs. He fought DLH, Oba Carr, David Reid, Winky Wright, and Vernon Forrest in the amateur system. He was on the US Olympic team and had offers to turn pro but he lost his instinct to destroy people in the ring. He beat Vernon Forrest twice actually. When Winky Wright noted an amateur career highlight in an interview, he said that beating hector colon was one of his amateur career highlights as colon was one of his best wins. It was good stuff, he had offers to go pro by lou duva, but he gave it up. had over 80 fights with 70something knockouts and only a few losses. He said seeing his opponents laid out in the ring and their eyes rolling up into their head started getting to him. Had a change of heart and gave up the brutality. Would have been a millionaire.
My dad did boxing training and frequently sparred in the 70s. I've never asked why he didn't fight properly
my grandads brother won boxing championships in the army before world war 2 not sure what weight but even more interesting my great grandmothers cousin has more wins on box rec than any other fighter in history....... http://boxrec.com/list_bouts.php?human_id=24129&cat=boxer