Stevie and Lindsey's parents were upper middle class..maybe upper upper middle class but not really wealthy. In comparison a contemporary of theirs country rock inventor Gram Parson's parents really were multi-millionaires.They would both have had to work at some point .Stevie a pretty girl, most likely would have married someone of comparable income to her dad .Lindsey would have done fine without FM eventually I'd guess as would have Chris and John as others have pointed out. Leaving Mick as Fleetwood Mac's most likely pauper which even with Fleetwood Mac he has been at times
