Money is a bonus but the part a big time celebrity cares about is getting their face out there and look like they are relatable and nice people. Helps when they have a new project.
That's exactly my point though. For me personally, the more relatable celebrities are, the less they are able to create the distance and mystique that is in my opinion the foundation of what celebrity is.
I think most people want to continue to be able to pretend that their favorite celeb doesn't have bad breath in the morning, binge watches bad TV or leaves their dirty towel on the floor in the bathroom.