Why did they make another saw movie?

I've seen the first 3 or 4 they made. They killed the guy who was in charge of the "games" right? So I don't know what dumb plot they've come up with to keep these movies going. There is no suspense at all to these movies. There are not scary. They are just gruesome and disgusting. Watching people being tortured for 2 hours is a complete waste of everyone's time and can't be good for people to watch. Anyone agree? Or care to explain the plot of the 5th movie?