That's the worst case scenario? I can always construct worse ones. Suppose Donald Trump goes to a bad therapist and then decides to launch nukes at Russia. Damn, this therapy profession needs to be hard regulated. It could lead to the extinction of mankind.

Doc: The encounter could create a time paradox, the result of which could cause a chain reaction that would unravel the very fabric of the spacetime continuum and destroy the entire universe! Granted, that's a worst-case scenario. The destruction might in fact be very localised, limited to merely our own galaxy.

Marty: Well, that's a relief.