Edit: I'm not saying they're guilty and should be put in jail for it or something. Not that kind of responsibility. However, they do bear some indirect responsibility that would cause most normal people to feel somewhat guilty.

An analogous type of guilt would be if, for example, I mistakenly dropped something while on top of a tall building and it cracked someone's windshield in the street below, caused an accident, and 3 people died. I didn't kill those people directly, and I definitely did not intend for anything bad to happen, and probably it was also the fault of the driver who let himself be distracted enough by something cracking his windshield to then proceed to have a major accident. It's hard to blame myself for those deaths, but I most certainly will, because I was involved in a critical part of the chain of cause and effect that made these three people die.

Now imagine if you dropped that penny from a tall building, and it caused 100'000 people to die. Some guilt trip that would be...