Manny Pacquiao's return to the ring at the weekend after a four-year hiatus marked the latest example of a boxer well past his prime who could not resist the temptation of the squared circle and a chance to add to his competitive legacy.

Several high-profile fighters are standing behind Manny Pacquiao, believing he should have walked away as the winner in his WBC world welterweight title bout against reigning champion Mario Barrios last July 19 (July 20,

Pacquiao's pay-per-view fights have generated nearly $1.3 billion in revenue, including a staggering $400 million for his highly publicized 2015 fight against Mayweather. That fight also represented Pacquiao's highest payday to date, with him bringing in an estimated $130 million from the bout.