Why Russell is a Millionaire?

On this season of Survivor, there was much talk of how Russell Hantz was independently wealthy. Everyone suggested he made gobs of money as owner of an oil company (or something like that).
But my question is this: wouldn’t his gig with Jennifer Nettles in Sugarland have been where he derived the greater portion of his income?
Perhaps the most savvy strategic move he played all season was his hiding the fact that he was a country music star.











