Why did old biff die and cease to exist when he made young biff rich but when marty changed the past to make his parents rich, he didnt die?
There was a cut/aforementioned scene where Lorraine shoots Biff sometime in the 90’s, which is why he’s shown clutching at his chest and clearly in pain once he gets back to 2015.
oh yeah that actually makes a lot of sense. im assuming she shoots him with his own gun.