The first boxer to win more than $100 million in purses is none other than the legendary American boxer, Floyd Mayweather Jr. Mayweather Jr. is considered one of the greatest boxers of all time due to his undefeated career record of 50 wins and 0 losses. He amassed a large fortune throughout his career, earning over $1 billion in revenue including endorsements. Mayweather Jr.'s success in the ring, combined with his mastery of self-promotion, made him one of the most well-known and wealthiest athletes in the world.