Rangers and celtic fans are just as bad as each other.
Also neither club would particularly well without the other. Whatever image the SPL has outside Scotland hangs on the Old Firm. The club finances for most of the teams hang on games against the old Firm.
I've heard that said so many times, and I just don't buy it. Rangers didn't sign a catholic player until nearly the end of the 20th century and when they did the fans burned their scarfs. How thats not worse then I'm a little baffled. We'll have to wait and see what happens to the rest of scottish football, but it could be a good thing.