People!
Every where you go there are huge numbers of them. And most of them aren’t paying attention. So they walk into you. Literally. I’m not kidding. Every day someone walks into me. Even though I’m working my ass off to avoid them, sooner or later someone finds a way around my defenses, and wham — football size hit.
From A tale of the grass being greener, by Dave Winer, a big guy in a big city.