A kid gets an ant farm when he's young. He cares for the ant farm and watch as they grow. He watches and intervenes out of curiosity the way most kids do.
As he hits teenage years, he gets destructive and when the farm gets too big he floods the farm or burns a couple of them with a magnified glass, mostly out of boredom.
After so many years the kid grows up to a man and loses interest in the ant farm and the ants reproduce and reproduce without any intervention other than what they cause for themselves thinking that their watcher is still behind the scene dictating their entire lives.
Ultimately, after years of not having their resources replenished and their numbers controlled by their now absent watcher they overpopulate and extinguish their resources, mass die off begin to occur. They are left wondering if and when their watcher will save them, however, their watcher lost interest years and years ago.