Why did Sunday feel so empty?

On Friday and Saturday, the place felt so packed you could barely walk around, get a porta potty, or god forbid fill up your hydropack. On Sunday the stages felt significantly less crowded. I was in the middle for porter and I hate models, but it was considered the back of the crowd. On previous days, I would be closer to the vendors than the stage when I would stay in the back. There was hardly any line for water or the bathrooms. Did everyone leave after Griz? What happened?