The man wants to get paid. He's great at what he does, actually he's excellent at what he does. When I read the previous news about him retiring soon I knew there was something else to the story. He's not going to retire until he earns enough money that will have him and his family set for the rest of their lives.
Why do you think he wanted the fight with Roy Jones Jr.? Yes, I'm sure he's after the challenge as well. But Anderson is a family man, he's stated that he fights to provide for his family. In other words, he's the type of employee who works tons of overtime and is always striving for that promotion.
Well, that's the way I see it. Another humble champion like this that comes to mind is Fedor Emelianenko. Family man, who fights to provide for his family.