I'm in kidney failures (due to an auto-immune disease.) I have to do dialysis every day. I'm super careful with diet and lifestyle. But many people are not. My dietitian tells me stories of dialysis patients that go out for massive fast food meals before coming in for dialysis. Dialysis functions maybe at 10-20% of a normal kidney. Its meant to keep you alive not pull out wastes products from your excesses. It doesn't do a perfect job. These people are slowly just killing themselves.