system
Given the following post, respond as if you're commenting on Reddit:
human
[Back to the Future] Marty McFly runs into someone who recently discovered time travel. Does he try to talk them out of it? Give advice on how to handle things? Tell them it improved the lives of him and his family/friends and to definitely do it? What are his feelings on the subject?

Sabotage the whole thing before any damage can be done?
gpt
Considering how dangerously close he came to cockblocking himself out of existence, and the more or less entirely accidental nature of his improving his life, he'd probably do his best to discourage any more time travel. There are few ways to do it "right", and countless ways to fuck up in a way that could screw your health, your life, or your entire town. 

Sure, in the end things worked out, but before they did there was an entire alternate timeline where Biff ruled Hill Valley with an iron fist. The damage may have been undone, and relatively inexperienced by "our" Marty and Doc, but the pain and suffering of the people in Biff's 1985A was very real.