Yeah, I know it's getting old but I couldn't resist.
Honestly, I don't know if they did it for money but I can't think of any other reason why a band would change as drastically as they did seemingly overnight.
It was as if they got a taste of how popular they could be after the black album and then not only ran with it but became everything they stood against previously. It also seemed strange to me that they started wearing makeup and fur coats. And started filing lawsuits against even small companies for petty stuff.
Bands change over time but it just looked to me like they went from one extreme to another and I can't imagine why someone might think that "until it sleeps" is better musically than say, "one".
Maybe the change wasn't all about money but if it looks like a duck and walks like a duck...