I don't think many fighters start boxing in the hope to become a millionaire. As a kid you don't think about these things you want to emulate your heroes. Many fighters reasons for fighting may change with time as power and money can corrupt your reasons for boxing. Look at Roy Jones a boxer who talked about the money and titles during his prime as the main motivation. He is often accused of not going for greatness and too often looking at boxing like a business but he is still a very rich man but fights on. Why? Because he loves the sport and believes he still has something to prove.
People say things they don't mean. All the time. You don't get as far in the sport as Eubank did (and others, like Mayweather) unless you have a serious passion for boxing. The money is the icing on the cake of a lifetime of graft and commitment and early morning runs round council estates.