To jump, or not to jump?

Today I was waiting for the train, and some young guys were tossing a football, back and forth.

At some point, one must have dropped it, as it bounced off the floor, on to the track below.

They seemed to deliberate jumping down there to retrieve the ball, and I had a shutter waiting to catch that, but they must have thought the better of it.

When would you risk jumping down there? Other than the obvious, you know, screaming baby and such. What would drive you to taking that kind of risk?