The cliché I hate isn't defined by a single quote, but i see It a lot. It is the general assumption that because boxing is a tough and dangerous sport, the fighters only motivation to fight is money. For example, if a fighter comes out of retirement you'll hear, "He must need the money". Or, if a fighter who has done well for themselves ends their retirement, "Why is he fighting again? He doesn't need the money". There are countless other examples that I can't be bothered mentioning, but they all miss out one potentially important motivation; just like other sports, the participants love the sport they compete in.
