I used to be a swimmer and can certainly say, as many others have, that he is the best swimmer of all time. As for how he ranks with athletes from other sports,

I used to be a swimmer and can certainly say, as many others have, that he is the best swimmer of all time. As for how he ranks with athletes from other sports, that is another question. I would say he would rank quite favorably in any ranking of best athletes regardless of discipline. As for making some coin, I wouldn't worry about that. I'm sure he has more than enough already. Athletes like him don't do it for the money. They don't even do it to beat the rest. They do it to beat themselves.