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.

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.