Floyd Mayweather is arguably the best pound for pound boxer in the world. He took an undefeated 47-0 record into 2015. After 2 wins he decided to call it quits and hung up his boxing gloves.
Say what you want about Mayweather and his boxing style but the fact of the matter is that Floyd Mayweather beat every fighter he faced, including some of the greatest names in boxing. He finished his career unbeaten, which is nearly impossible in any sport.
Mayweather retiring is a big story because of the impact he had on boxing. The sport was dead in many people's eye, especially with the emergence of the UFC. But Mayweather never quit on the sport and single handily brought the sport back to life. He now leaves the sport in great shape with super stars such as Canelo Alvarez, Deontay Wilder, and Triple G, Gennady Golovkin.