It is one of man's basic needs to be useful at something, and to be needed - i.e. work etc
If I became filthy rich, it would be as a result of hard work on my part so I would merely delegate more duties and take a more relaxed role in the business I suppose.
If eventually I was not required anymore, I would get involved in some kind of community philanthropy - even if it was just setting up a gym for young ex-cons etc. You have to be doing something useful as a man, or, after a while you WILL get depressed or over indulge in something.
Edit: I don't have my own business, just a thought.