Doc is Caught in a Time Loop of His Own Making

If you had a real working time machine, the temptation to use it as much as you could would be overwhelming, even when it doesn't make sense. Would you get stuck on trying to make everything perfect, just for the excuse to go back and forth? Doc's become a little obsessed, to the point where you might want to take his keys away and make him remain in one timeline for a while. Why make the 1985 Marty always save the day when you could just ask 2015 Marty to do the same? Or maybe even take care of the problem yourself. Maybe this is why Doc eventually decided to stay in the 19th century in the third film. No, right, that was for love. Studio C did a good job of recreating the characters of Back to the Future 2 in order to explore the absurdities of what that kind of power can do to someone.