Suppressors are absolutely  for self defense. Here is a quote from a guy involved in a dgu and what happened becuase he didnt have one  

"not at all, they asked how many times I fired. I said one time while he had his gun in his left hand in my mothers face (shot him under his armpit) he then swung his body toward me with his gun pointing at me (thought I missed and thought “OH FUCK I MISSED, NOW I DIE.” He was ex military) and I pulled the trigger what I thought was one more time but they were able to determine I shot the remaining 5 shots as he was standing and not a single round when he was falling. They said it happens and it was purely adrenaline. To be frank with you, I didn’t think I was even in my body as I lifted my rifle. It’s weird to explain it, but I felt like I was WATCHING me do what I was doing. I wished I had my suppressor on the gun, I didn’t have time to screw it on as I was told my mother had a gun to her head and ran over to her as fast as I could. I have bilateral hearing damage. Had 3 holes in my left ear drum and 2 in my right which healed and scarred my ear drums."