I don't think it necessitates pathological, though I am sure there are higher rates of it among the wealthy. I don't think someone worth $100 million keeps working because they're incentivized by the money as much as they're incentivized by "success". They enjoy the power and prestige and reputation and having people work for them. They enjoy getting to make big, powerful decisions. They like having their big ego.
Of course many do genuinely just want that $400 million yacht and won't get there unless they make a few billion first.
I know this is extremely simplistic and insufficient as a complete explanation, but I truly think it's a major component.