Probably because Silva knows that Mayweather is, first and foremost, a businessman. I doubt that the challenge of competition ever entered Mayweather's mind, it's all about making money. I'm not an idiot or so naive that I don't know that boxing is all about money but Mayweather exalts in being the "Money Man". Just my opinion, but maybe Floyd has money and respect confused, one does not automatically go with the other.