Extra-terrestrial bodies do collide with Earth from time to time, sometimes with profound consequences. Witness the asteroid impact 65 million years ago that basically killed off the dinosaurs and wiped the slate clean for mammals to take their turn. No idea of how high the waves were, but they were big enough, and that was just the beginning.

We can assert that such events can happen, and probably will happen, given enough time. On the scale of human lifespans, the probabilities of such cataclysmic events is quite low, while the chances of more mundane disasters like fires, floods, earthquakes, winter storms, etc. is much more likely and well worth the time and effort to prepare. It all comes down to the math...

Welcome, Pooh-Bah Jeanette-Isabelle! What a great speech!