Strange thoughts come to mind when you're in the lab at 4 in the morning
For instance, in Bill And Ted's Excellent Adventure
, people from the future travel back in time to ensure the existence their utopia because they reason that they might blink out of existence from something that already happened and obviously led to their existence anyway. To accomplish this they give two stoners the means to travel further backwards in time and kidnap important military and influential figures from history, not at all worried that by doing so the afore mentioned stoners (the pillars of their utopia) will probably be erased from time themselves.
Clever. George Carlin still looked cool in his future clothes though.