This is a great topic for astro101 classes. We can talk about reality compared to hollywood, about big numbers, big space, and how long odds can act up over long period of time. Two new articles add to the debate.
This first one shows that there has been far more asteroid collisions on Earth than previously accepted, seemingly mostly from one orbital location. Best to keep any eye on these ones then.
This second one talks about a species ending event long before the time of the dinosaurs. This one knocked off 95% of species on the Earth. This one was not an asteroid collision, instead a sudden release of CO2, probably from a volcano. The scary thing about this second one is the rise of CO2 in the last 60 years or so is paralleling this situation. Perhaps we should worry more about the risks we are doing to ourselves than about big bits of rock in space.