The chances that your tombstone will read “Killed by Asteroid” are about the same as they’d be for “Killed in Airplane Crash.”
Don't think so, Neil, given that thousands have been killed in airplane crashes, vs. 0 known persons killed by asteroid strikes, despite the exposure being greater in the case of asteroids.
LessWrong is not big on discussion of non-AI existential risks. But Neil deGrasse Tyson notes killer asteroids not just as a generic problem, but as a specific one, naming Apophis as an imminent hazard.
So treat this as your exercise for today: what are the numbers, what is the risk, what are the costs, what actions are appropriate? Assume your answers need to work in the context of a society that's responded to the notion of anthropogenic climate change with almost nothing but blue vs. green politics.