What fighters could have been greater but for some reasons, they chose not to?

got this idea when i saw jose's answer about lew jenkins who could have been far greater if he stayed focused and dedicated. instead he went out of control, drinking almost all night and staying up all night. a lot of fighters could have been greater but they were too lazy to train. some would rather fight bums. some would avoid challenges. so what fighters could have been greater if they gave boxing 100 percent? thanks and have a great day.