In time travel films, people will always stress how important it is to make no mark in the past. Moving a cup will disrupt the space-time continuum and have huge ramifications in the future-present. Like Biff becoming the Trump of the Back to the Future universe.
We don't seem to be very good at considering how making real changes in our present could have these huge benefits to our future. It's the same thing, just in a more stretched timeline with the future still being totally unknown.
I should move the cup more often.