So much of what happens in this life is out of our control, to a degree that is staggering and terrifying when you think about it. Staring too much at the role of circumstance and luck and factors over which you have no influence gives you the sickening feeling of the ice cracking under your feet.
The jackass nephew of some well-paid suit could apply for the job that would change your life. A car could come careening around a corner at the moment you intersect its trajectory. You could be born on the wrong side of an imaginary line and either suffer through life, or be elevated by it.