Floyd Mayweather was the "Money" man of boxing for a reason — and it's all because he made a billion dollars from career earnings, according to Forbes. Mayweather may now be retired, but he still works hard and spends hard. After all, this is a man who once bought the ultra-rare $4.7 million supercar Koenigsegg — but that isn't even his wildest purchase. Mayweather also recently showed off an $18 million watch called "The Billionaire" on his Instagram page.