Imagine, if you will, a course with ten obstacles.
A bunch of runners stand at the beginning. There's a two-story wall you have to jump over, there's some kind of rope bridge, snakes on a plane, whatever.
For simplicity, assume that each obstacle successfully stops 50% of the runners.
So if twelve runners start out, after the very first obstacle, six of them will somehow find themselves defeated. You will see them piled in a heap at the bottom of the two-story wall.
The remaining six will move on to the rope bridge, where three will fall through the ropes in a humorous way, eventually finding themselves dangling by one foot in the air, with all kinds of silly things falling out of their pockets. Keys, wallets, coins, yes, but also ...