No need to be forgiven
The only bizarre thing is the straws that some grasp at to try and make the impact hazard disappear.
It is well known that comets provide the bulk of the impact threat, and these authors even make the point that comet flux is not uniform over time, and thus indeterminable in an 8 year sample.
Try 5,000 years and 5,000,000,000 years instead - data in both cases is available.
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